Navigation News Annual Scientific Meeting Participants Program Posters Information for presenters HPC Live Helpdesk Events Welcome reception Social Outing to MBO Harley Wood Public Lecture ASA Conference Dinner Prizes ASA Student Prizes Anne Green Prize Bok Prize Charlene Heisler Prize David Allen Prize Harley Wood Lecture Louise Webster Prize Policies Sponsors HWSA 2018
News Annual Scientific Meeting News Participants Program Posters Information for presenters HPC Live Helpdesk Events Welcome reception Social Outing to MBO Harley Wood Public Lecture ASA Conference Dinner Prizes ASA Student Prizes Anne Green Prize Bok Prize Charlene Heisler Prize David Allen Prize Harley Wood Lecture Louise Webster Prize Policies Sponsors HWSA 2018

ASA Annual Scientific Meeting 2018 – Program

Click on session headings to view the session; click on talk titles to view their abstracts.

For Speaker and Poster Presenter Information follow click here.

If you'd like to download a copy of the program, you may do so from here (455.7 KB).


Sun, 24 Jun | Mon, 25 Jun | Tue, 26 Jun | Wed, 27 Jun | Thu, 28 Jun | Fri, 29 Jun

Sun, 24 Jun

1:00–3:00 p.m. | 6:00–10:00 p.m.

Sun, 24 Jun, 1:00 p.m. to 3:00 p.m. Day ↑ | Top ↑

ASA Council meeting

AR 209 (staff room)

Sun, 24 Jun, 6:00 p.m. to 10:00 p.m. Day ↑ | Top ↑

Welcome reception

Registration required

6:00 p.m. – 10:00 p.m.

Welcome reception will be held on 24 June at the Hawthorn Arts Centre, just across the road from Swinburne University. Hawthorn Arts Centre is a former civic building with a recently redeveloped community hall, with an intriguing mix of traditional and contemporary design. If you would like to bring guests to this event, please ...

More info →

Mon, 25 Jun

8:30–9:00 a.m. | 9:00–9:15 a.m. | 9:15–10:30 a.m. | 10:30–11:00 a.m. | 11:00–11:30 a.m. | 11:30a.m.–12:15 p.m. | 12:15–12:30 p.m. | 12:30–2:00 p.m. | 2:00–3:30 p.m. | 3:30–4:00 p.m. | 4:00–5:30 p.m. | 6:00–7:30 p.m. | 7:30–9:30 p.m.

Mon, 25 Jun, 8:30 a.m. to 9:00 a.m. Day ↑ | Top ↑

Arrival tea/coffee

Location: ATC 101 foyer

Mon, 25 Jun, 9:00 a.m. to 9:15 a.m. Day ↑ | Top ↑

Opening Ceremony and address

Location: ATC 101

09:00 - 10:30 Session Recording

09:00 - 09:05: Welcome to ASA 2018 - Prof. Karl Glazebrook, Director Centre for Astrophyics and Supercomputing 

09:05 - 09:10: Welcome to Country - Wurundjeri Land & Compensation Cultural Heritage Council Aboriginal Corporation

09:10 - 09:15: Opening address - Vice-Chancellor Prof. Linda Kristjanson 

Mon, 25 Jun, 9:15 a.m. to 10:30 a.m. Day ↑ | Top ↑

General session: Galactic astronomy

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

09:15 - 10:30 Session Recording

9:15 –9:30 a.m. — Astronomical Evidence for Panspermia
John LATTANZIO, Faculty, Monash University

A series of astronomical observations obtained over the period 1986 to 2018 supports the idea that life is a cosmic rather than a purely terrestrial or planetary phenomenon. These include (1) the detection of biologically relevant molecules in interstellar clouds and in comets, (2) mid-infrared spectra of inter- stellar grains and the dust from comets, (3) a diverse set of data from comets including the Rosetta mission showing consistency with biology and (4) the frequency of Earth-like or habitable planets in the Galaxy. We argue that the conjunction of all the available data suggests the operation of cometary biology and interstellar panspermia rather than the much weaker hypothesis of comets being only the source of the chemical building blocks of life. We conclude with specific predictions on the properties expected of extra-terrestrial life if it is discovered on Enceladus, Europa or beyond. A radically different biochemistry elsewhere can be considered as a falsification of the theory of interstellar panspermia.

Slides (PDF file) (4.8 MB).

9:30 –9:45 a.m. — The Stingray planetary nebula; radio monitoring of a rapidly evolving star
Lisa HARVEY-SMITH, Faculty, Commonwealth Scientific and Industrial Research Organisation

SAO 244567 is a post-AGB star that has evolved into a young planetary nebula (the Stingray nebula) over the past three decades. It is remarkable because it is the youngest known planetary nebula and we can watch it actively evolving. We have analysed Australia Telescope Compact Array data of this object from 4 to 23 GHz between 1991 and 2016, producing the first spatially resolved radio images of the Stingray nebula. A radio ring, which appears to be associated with the ring seen in HST images, is visible. We also found a narrow extension to the radio emission towards the eastern and western edges of the nebula. The emission measure decreased between 1992 and 2011, suggesting the nebula is undergoing recombination and moving back towards the AGB. The radio spectral index is broadly consistent with a free-free emission mechanism, however a single data point hints that a steeper spectral index has possibly emerged since 2013, which could indicate the presence of synchrotron emission. If a non-thermal component has emerged, such as one associated with a region that is launching a jet or outflow, we predict that it would intensify in the years to come.

Slides (PDF file) (12.2 MB).

9:45 –10:00 a.m. — Gas Temperature Demography and the Relationship to CO at Low Metallicity in the Magellanic Clouds
Katie JAMESON, Postdoctoral Fellow, Australian National University

Not only is the transition from warm to cold neutral gas a rate limiting step to the formation of molecular gas, but it appears to influence star formation efficiency globally and we still do not understand how metallicity affects this transition. Given their proximity and low metallicity, the Magellanic Clouds provide the ideal laboratory to study the evolution of gas in the interstellar medium. We present first results from a new HI and OH absorption line study using the ATCA to measure the warm-to-cold atomic fraction and the atomic-to-molecular transition in the Large and Small Magellanic Clouds (LMC and SMC, respectively). From these observations, we are able to measure the optical depth, spin temperature, cold gas temperature, and cold atomic gas fraction. These measurements of the optical depth allow us to constrain the amount of ``CO-faint'' gas that is optically thick HI. Comparing to previous studies (Dickey et al. 1994, Marx-Zimmer et al. 2000, Dickey et al. 2000), we find our initial analysis indicates that we measure higher average spin temperatures in the LMC and much lower average spin temperatures in the SMC. From this, we estimate cold atomic gas fractions of ~20% for the LMC and ~40% for the SMC, which would mean the SMC has the highest cold gas fraction in the Local Group. We currently have no detections of OH absorption, but the upper limits on the column density of molecular gas are consistent with the dust-based molecular gas estimates (Jameson et al. 2016). ALMA CO observations of a subset of sources have revealed detectable CO emission in only 3 out of the 21 lines of sight indicating that many regions with cold atomic gas have little CO.

Slides (PDF file) (7.1 MB).

10:00 –10:15 a.m. — Magnetised clouds in the Galactic corona: Fuel for future star formation?
Asger Emil GRONNOW, PhD student, University of Sydney

The Galactic halo contains a complex ecosystem of multiphase intermediate-velocity and high-velocity gas clouds whose origin has defied clear explanation. They are generally believed to be involved in a Galaxy-wide recycling process, either through an accretion flow or a large-scale fountain flow, or both. Recent numerical studies have found that they accrete gas efficiently from the hot corona as they move through it. In these models, gas stripped from the clouds mixes with the low density coronal gas significantly reducing its cooling time scale. The newly cooled gas follows the cloud to the disk where it is accreted and may fuel star formation. These studies, however, ignore the effects of the coronal magnetic field and are typically two-dimensional. In this talk, I will present our 3D high-resolution simulations where we find that the magnetic field significantly decreases the amount of mixing by damping instability along the cloud boundaries. This in turn suppresses the condensation in the wake of clouds, preventing the sharp upturn in cold gas seen in previous non-magnetic studies and significantly lowering the efficiency of fountain-driven accretion.

Slides (PDF file) (1.4 MB).

10:15 –10:30 a.m. — Uniform magnetic fields in HII regions revealed by GMIMS
Alec THOMSON, PhD student, Australian National University

Magnetic fields significantly influence the formation of structure in the Milky Way. These structures are often diffuse in nature and cover large angular scales. To this end the Global Magneto-Ionic Medium Survey (GMIMS) has observed the diffuse radio polarisation in the entire Southern Sky from 300 to 480 MHz. From these observations I have produced rotation measure spectra by rotation measure synthesis. These spectra reveal the magneto-ionic structure of the diffuse interstellar medium. I will give a brief overview of GMIMS, as well as an update on the project's current status. The results from GMIMS have provided a number of surprising insights into the Galactic magneto-ionic. I will discuss our finding of coherent magnetic fields in large HII regions. These include two well-known objects, Sh2-27 and Barnard's Loop, as well as two previously unknown objects. These first results from the Southern, low-frequency GMIMS demonstrate the unique power that diffuse polarisation observations have for probing the magneto-ionic medium of the Galaxy.

Slides (PDF file) (25.5 MB).

Mon, 25 Jun, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Location: ATC 101 foyer

Mon, 25 Jun, 11:00 a.m. to 11:30 a.m. Day ↑ | Top ↑

Charlene Heisler Prize Talk

Location: ATC 101 — Chair: Stuart WYITHE, University of Melbourne

11:00 - 12:30 Session Recording

11:00 –11:30 a.m. — 3D non-LTE stellar spectroscopy
Anish AMARSI, Postdoctoral Fellow, Max Planck Institute for Astronomy

Stars leave their fingerprints on the light that they emit, in the form of absorption and emission features.  Decoding this information to infer stellar parameters and chemical compositions is of key interest to astronomers.  However, such measurements are heavily model dependent, and for late-type stars like as the Sun their accuracy is often limited by the use of one-dimensional (1D) hydrostatic model atmospheres and the assumption of local thermodynamic equilibrium (LTE).  Recently though, it has become feasible to relax both assumptions simultaneously, i.e. to perform 3D non-LTE spectroscopic analyses.  In this talk I shall discuss the physics of this more accurate method, and present our latest results for carbon and oxygen abundances in the Sun and in halo stars. 

Slides (PDF file) (10.8 MB).

Mon, 25 Jun, 11:30 a.m. to 12:15 p.m. Day ↑ | Top ↑

General session: High energy astrophysics 1

Location: ATC 101 — Chair: Ryan SHANNON, Swinburne University

11:30 - 12:30 Session Recording

11:30 –11:45 a.m. — The UTMOST SMIRF Survey
Vivek VENKATRAMAN KRISHNAN, PhD student, Swinburne University of Technology

Ever since the discovery of radio pulsars in the 1960s, there have been about a dozen all-sky surveys conducted with premier radio telescopes in pursuit to find more. Such surveys have resulted in a population of pulsars that have extremely periodic emissions but also a few whose emissions are rather sporadic. There have long been speculations that the population of such sporadic emitters might be greater than the population of periodic emitters and that they have been "missed" in previous surveys due to selection biases, owing to the highly infrequent probes of the sky searching for such sources. The UTMOST SMIRF survey is a fully robotic and commensally operated multi-pass Galactic plane survey with the newly upgraded UTMOST telescope, that aims to understand about and increase the population of such sporadic emitters, by performing fast and repeated surveys of the Galactic plane and searching in real-time for new pulsars. I will give an overview of the survey architecture, explain its commensal operation with other prominent observing programmes in place at UTMOST, and discuss ongoing results.

11:45 a.m. –12:00 p.m. — Modelling Pulsar Glitches: An Overview
Lisa DRUMMOND, PhD student, University of Melbourne

Pulsars can exhibit spasmodic spin-up events, called glitches, which are typically attributed to the collective motion of superfluid vortices in the stellar interior. Therefore, pulsar glitches are a unique window into the dynamics of neutron matter at extreme densities. Modelling the physical mechanism that produces these glitches is an endeavour that spans many scales: from the quantum mechanical, microscopic interaction of vortices in the superfluid interior to the macroscopic motion of the rigid stellar crust. A mean-field approach can be used to model pulsar glitches as a state-dependent Poisson process, thereby capturing the global behaviour of glitching pulsars (Fulgenzi, Melatos & Hughes, 2017). A complementary approach is to simulate vortex-avalanche-induced glitches by constructing a Gross-Pitaevskii model from first-principles, thereby incorporating the microscopic physics of superfluid vortices (Warszawski, Melatos, 2011; Melatos, Douglass & Simula, 2015). These models can each be extended in various ways, for example by including the interaction with a proton superconductor in the core (Drummond & Melatos, 2017). Bridging the stellar and microscopic scales described in these two approaches is an enormous computational and theoretical challenge.

Slides (PDF file) (4.5 MB).

12:00 –12:15 p.m. — Studying accretion with transitional millisecond pulsars
Adam Travis DELLER, Faculty, Swinburne University of Technology

Transitional millisecond pulsars (tMSPs) beautifully illustrate the evolutionary phase in which neutron stars are "recycled": spun up to millisecond periods by the accretion of matter from a Roche-lobe-filling companion. These objects switch between a rotation-powered state, in which they are visible as "normal" millisecond pulsars, and an accretion-powered state, in which they accrete material from the companion. In the accretion state, the radio pulsation mechanism is suppressed, but continuum radio emission is produced by a fraction of the accreting material which is accelerated and ejected. Along with X-ray emission tracing the innermost regions of the accretion disk, this radio continuum emission allows us to build a picture of the unexpectedly complex accretion processes that operate in tMSP systems. I will describe our current knowledge of accretion in tMSPs, how it appears to differ from other low-mass X-ray binaries, and the prospects for future advances.

Slides (PDF file) (13.1 MB).

Mon, 25 Jun, 12:15 p.m. to 12:30 p.m. Day ↑ | Top ↑

Chapter Chair Sparklers; Poster Sparklers

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

12:15 - 12:30 Session Recording

Mon, 25 Jun, 12:30 p.m. to 2:00 p.m. Day ↑ | Top ↑


Location: ATC 101 foyer

ECR Chapter Town Hall Meeting

Location: ATC 101

Mon, 25 Jun, 2:00 p.m. to 3:30 p.m. Day ↑ | Top ↑

General session: Solar and stellar astrophysics 1

Location: EN 101 — Chair: Lisa HARVEY-SMITH, Commonwealth Scientific and Industrial Research Organisation

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — Making including duplicity (of stars) in astrophysics easier.
JJ ELDRIDGE, Faculty, The University of Auckland

It is becoming widely accepted that most stars are in binary or multiple star systems with a significant fraction having their evolution affected by binary interactions. The majority of studies of stellar populations still ignore this and the impacts the binary interactions can have on the appearance and nature of stellar populations. The BPASS (Binary Population and Spectral Synthesis; code has been attempting to make it easier to take account of interacting binaries with results and models being made publicly accessible and by making as broad predictions as possible (Eldridge et al., 2017). We will first describe the BPASS project and recent results on modelling HII regions and on studing the old stellar populations in globular clusters with our latest v2.2 models. (Note: if time allows of if requested we can describe our experience of producing a large an complex numerical model set with limited resources. As well as our attempts are providing clear and accessible resources and user guides in addition to our published scientific articles). Finally we will present for the first time our attempt at supernova lightcurve population synthesis. As all the BPASS stellar models are calculated in a detailed stellar evolution code we are able to use the final progenitor structure in the SuperNova Explosion Code (SNEC) to predict the full range and diversity of supernovae expected from a stellar population including all the progenitors affected by binary interactions. We will show we can how we reproduce the broad range of expected SN types but also the rare supernovae that don't match into those expected types that have not yet been observed.

Slides (PDF file) (7.2 MB).

2:15 –2:30 p.m. — Toward understanding the origin and evolution of magnetic white dwarfs
Adela KAWKA, Research Fellow, Curtin University

In the past few years, we have discovered several cool, magnetic white dwarfs using ESO's FORS2 and X-shooter spectrographs. Among these are several polluted white dwarfs, which have revealed that the incidence of magnetism in polluted hydrogen-rich white dwarfs is close to 50%. This is significantly higher than the ~5% incidence found in the younger white dwarf population. Our sample also includes the first magnetic white dwarf in a close double degenerate system, NLTT12758. Using VLT/X-shooter we obtained radial velocity measurements of both the magnetic and non-magnetic components and measured the system mass ratio. The dynamical mass ratio is essential to determine the mass of the magnetic white dwarf and to provide constraints on the origin and evolution of magnetic fields in degenerate stars and magnetic cataclysmic variables. The study will also help constrain the effect of magnetic fields on convective energy transport.

2:30 –2:45 p.m. — Low frequency GMRT studies of Ultra-Cool Dwarfs
Andrew ZIC, PhD student, The University of Sydney

The quiescent and bursty radio emission observed in about 10\% of Ultra-Cool Dwarf stars (UCDs; spectral class > M7) indicates the presence of strong, persistent magnetic fields. Radio frequency observations have been key to characterising the radio emission mechanisms as well as the magnetospheric structure for some radio-loud UCDs. However, important questions remain unanswered, including the generation, structure, and evolution of UCD magnetic fields; and how the UCD magnetosphere is populated with non-thermal electrons responsible for the radio emission.\\ The majority of studies of UCDs at radio frequencies have been in the 4-8 GHz band. Hence the nature of UCD radio emission at low frequencies ($\lesssim 1.4~\text{GHz}$) remains relatively unexplored, and could provide key insights into these questions.\\ In this talk, I will present the results of GMRT observations of 10 UCDs taken at $610$ and $1300~\text{MHz}$. These are the first observations of UCDs in this frequency range to be published in the literature. Using these observations, we are able to constrain the shape of the spectral energy distribution for the detected UCDs, LSPM J1314+1320 and 2MASS J0746+20. We are also able to determine if there is a low-frequency counterpart to the bursty and pulsed radio emission observed at higher radio frequencies. These results provide new insights to the physical conditions in UCD magnetospheres.

Slides (PDF file) (826.8 KB).

2:45 –3:00 p.m. — Cool, polluted white dwarfs in the SkyMapper Survey
Stephane VENNES, Research Fellow, unaffiliated

We have conducted a search for chemically peculiar white dwarfs in a VLT/FORS2 low-dispersion spectroscopic survey of newly identified white dwarfs. Using follow-up observations using the VLT/Xshooter spectrograph we built detailed abundance patterns: The presence of heavy elements in several objects is definite evidence of accretion of debris from their immediate circumstellar environments. Preliminary results based on low-dispersion spectra also indicate a stronger prevalence of polluting material in He-rich white dwarfs compared to H-rich white dwarfs. I will briefly review the current status of our understanding of the white dwarf circumstellar environment.

3:00 –3:15 p.m. — Discovery of M-dwarf Flares from SkyMapper Southern Survey
Seo-Won CHANG, Postdoctoral Fellow, The Australian National University

M-dwarf flares are common candidates of high-amplitude, fast optical transients serendipitously discovered by many time-domain surveys. We present the results of our search to constrain the rate of these galactic transients in the Southern sky using a volume-limited sample (d < 25pc) of 1359 M dwarfs and flux-limited sample (complete to 18 mag in all uvgriz bands) from the SkyMapper Shallow Survey. By covering a large sky area homogeneously with a six-colour sequence, it allows us to assemble bona-fide flares on timescales of less than five minutes for each pointing. We apply either correlation-based or scatter-based outlier searches to identify flaring epochs in the light curves of M dwarfs. To provide meaningful constraints, we will investigate in detail how the observed flare rate is sensitive to spectral type, survey depth, cadence or quality of the data.

Slides (PDF file) (3.1 MB).

3:15 –3:30 p.m. — Breakdown of a common envelope simulation
Thomas REICHARDT, PhD student, Macquarie University

The common envelope interaction is known to be an incredibly important process for the formation of the majority of compact binary systems, yet details of this interaction are still only known on a very surface level. Hydrodynamic simulations of the interaction have been used for many years now, with some success, to glean information about the interaction. Here, I present several common envelope simulations, breaking down the various phases of the interaction to greater understand it.

Special session: SKA precursor science with ASKAP and MWA 1

Location: ATC 101 — Chair: Sarah WHITE, Curtin University

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — The Murchison Widefield Array Epoch of Reionisation Project
Cathryn TROTT, Faculty, International Centre for Radio Astronomy Research - Curtin University

The Murchison Widefield Array (MWA) Epoch of Reionisation (EoR) project has collected four years of data over three primary observing fields. Of these, we have calibrated, quality-checked and processed hundreds of hours to 21cm brightness temperature power spectra over a range of redshifts. I will provide an update of progress in the MWA EoR community, and the limits we expect to publish in 2018.

Slides (PDF file) (14.6 MB).

2:15 –2:30 p.m. — Enhancing EoR limits through improved analysis and calibration of MWA observations
Nichole BARRY, Postdoctoral Fellow, University of Melbourne

Epoch of Reionisation observations have the potential to be transformative in the field of cosmology, but this is impossible without unprecedented levels of precision in calibration and analysis. We enhance EoR upper limits from the Murchison Widefield Array through the improvement of instrumental calibration with in situ simulations. The reduced limit is a direct result of development in our pipeline, and highlights the precision and accuracy that we must achieve. Our improved EoR upper limit is 6.4x10^3mK^2 at k=0.2hMpc^-1 for z=7, an improvement of over a factor 4 compared to a previous analysis using the exact same data set.

2:30 –2:45 p.m. — Towards a New MWA Limit on the Epoch of X-Ray Heating
Bart PINDOR, Research Fellow, University of Melbourne

The recent detection of a deep low-frequency absorption feature by the EDGES experiment (Bowman+ 2018) suggests the possibility of larger than expected 21cm fluctuations prior to reionization. The initial MWA limit at these redshifts (Ewell-Wice+ 2016) does not reach the implied EDGES signal. Here I report on an effort to use the Australian MWA EOR pipeline to set a new limit on the 21cm power spectrum in the 75-100 MHz band.

2:45 –3:00 p.m. — Finding pulsars in the SKA-era: an SKA-demonstrator all-sky pulsar survey with the Phase 2 MWA
Ramesh BHAT, Research Fellow, ICRAR, Curtin University

Pulsar astronomy is a headline science theme for the SKA. Finding exotic pulsars and using them for high-profile science applications including testing strong-field gravity and detecting ultra-low frequency gravitational waves are among the key science drivers for the SKA and its pathfinder facilities. With its low-frequency, interferrometric and wide-field advantages, SKA-Low is highly appealing for conducting large-scale pulsar searches. The upgraded Murchison Widefield Array (i.e. the Phase 2 MWA) provides a perfect platform to demonstrate this. In particular, the compact and extended array configurations now possible with the MWA can be leveraged for conducting efficient all-sky pulsar searches as well as targeted searches. In this talk, I will outline the ongoing preparatory work to forge ahead in this direction, including recent developments in post-processing, pilot search efforts and the related science developments that inform the survey design, plans and strategies. Among the exciting prospects are rapid turnarounds in making discoveries by accelerating the process of candidate identification and confirmation, and their rapid sky localization and full characterization. A demonstrable success on this front will also bolster the prospects for SKA-Low to emerge as an efficient pulsar discovery machine.

3:00 –3:15 p.m. — Investigating the Interstellar Medium towards PSR J2241-5236 with the MWA
Dilpreet KAUR, PhD student, Curtin University

Interstellar Medium (ISM) propagation effects on pulsar signals are a major concern for Pulsar Timing Array (PTA) experiments which aim to detect ultra-low frequency gravitational waves. These ISM effects show strong inverse frequency dependencies and are more pronounced at low observing frequencies. Therefore, the Murchison Widefield Array (MWA) which operates from 80 to 300 MHz, provides an excellent opportunity to study timing-array millisecond pulsars (MSPs) and to characterise the ISM in their directions. I will present the first low-frequency detections of PSR J2241-5236, a promising pulsar for current and future PTA experiments. Using our detections, we demonstrate the MWA’s ability to obtain high-quality pulse profiles and precise dispersion measures (DMs), and also perform useful scintillation studies. Timing precisions at the level of a few microseconds are currently achievable for this pulsar with the MWA, enabling us to determine DMs with a precision of the order of a few parts in million. This exemplifies the MWA’s potential to undertake high-quality MSP studies at low frequencies.

3:15 –3:30 p.m. — Hunting for intermittent pulsars at low frequencies
Bradley MEYERS, PhD student, ICRAR/Curtin University

Sporadic pulsar emission poses some challenging questions surrounding pulsar radio emission, which is itself still a mystery. The “intermittent” or “state-switching” pulsars, of which there are only five known, exhibit some of the most extreme examples of pulsar emission. These pulsars remain quiescent for extended durations, indicating that the catastrophic events which initially disrupt the radio emission persist on similar time scales. One of the brightest and most active of these state-switching pulsars is PSR J1107-5907, an old, isolated pulsar that switches between its bright and inactive states on a time scale of hours. We successfully detected PSR J1107-5907 simultaneously with the Murchison Widefield Array (MWA, 154 MHz) and the recently upgraded Molonglo Observatory Synthesis Telescope (UTMOST, 835 MHz) in September 2017. This is the first time a pulsar of this type has been detected below ~700 MHz, where the low frequency information allows us to substantially refine the catalogued dispersion measure of PSR J1107-5907. We found remarkable variation in individual pulse morphologies when comparing coincident pulses between frequencies. Finally, given the contemporaneous detections, we also investigate the spectral properties of the emission and thus comment on the detectability of this type of pulsar with the next generation of radio telescopes.

Slides (PDF file) (2.0 MB).

Mon, 25 Jun, 3:30 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

Location: ATC 101 foyer

Mon, 25 Jun, 4:00 p.m. to 5:30 p.m. Day ↑ | Top ↑

General session: Solar and stellar astrophysics 2

Location: EN 101 — Chair: JJ ELDRIDGE, The University of Auckland

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — Star-set on an accretion disk
Geoffrey Raymond BRYAN, PhD student, Swinburne University of Technology, Centre for Astrophysics and Supercomputing

Classical T-Tauri stars are variable young stellar objects (YSOs) with substantial infrared excess in their spectral energy distributions (SEDs), indicating they are surrounded by dusty protoplanetary disks. A small subset of YSOs that exhibit 'see-saw' temporal variations in their mid-infrared SED, where the flux short-ward of a fulcrum wavelength increases, while the flux long-wards of this wavelength decreases over timescale of weeks to years. 

Using radiative transfer modelling, we conduct a parametric study of the exemplar of the class of YSOs, LRLL31, and show that the most probable cause of its SED see-saw is most likely due to the change in height of the optically thick inner rim of the accretion disk at the dust sublimation radius, or some other phenomenon which results in a similar appearance to an optically thick inner rim of fluctuating  height.  We also find that a fulcrum point only occurs for relatively high disk inclinations  to the line of sight (>60 degrees), which is when the disk begins to occult the star as viewed by an observer. Other disks with temporal Spitzer MIR observations showing this see-saw phenomena also have relatively high inclinations, suggesting general agreement with the predictions of our model.


4:15 –4:30 p.m. — Unravelling the accretion and jet creation processes at play in post-AGB binaries
Dylan BOLLEN, PhD student, Macquarie University

The presence of a binary companion is believed to be the main shaping agent for asymmetric Planetary Nebulae (PNe). The binary interactions induce jet formation which drives the non-spherical structures that we observe in PNe. This is an important feedback mechanism of dust and gas to the galaxy. However, the central regions of PNe are highly obscured. For this reason, we turn our focus to the PN-progenitors, namely post-Asymptotic Giant Branch (post-AGB) binaries. In our recent work, we find that the inner regions of these objects can be observed directly, making them important tracers for jet formation in evolved binary systems. In this talk, I will present our quantitative study on the origin and properties of high-velocity outflows in post-AGB binaries. By comparing a geometrical model of these systems with the observational data, we were able to deduce the jet geometry which revealed that the gaseous circum-companion disk is the origin of the fast outflow. Additionally, by studying the mass accretion rates and jet outflow momenta, we can determine how the changing conditions in the inflow and outflow affect the launching of these jets and their environment. These results are crucial to model binary post-AGB binaries and PNe. This is important to get a better understanding of the binary interaction physics, such that we can provide a more complete description of the further evolution of these systems and their impact on the surrounding environment.

Slides (PDF file) (5.7 MB).

4:30 –4:45 p.m. — Magnetic activity of M-type pre-main sequence stars, and the search for their exoplanets
Belinda Annette NICHOLSON, PhD student, University of Southern Queensland

The magnetic fields and activity of the coolest pre-main sequence stars are poorly understood. To date, only one such star has been mapped, V2247 Oph, an M-type, fully convective star, which displays a very different magnetic field to the observed dipole fields of more massive and yet fully convective pre-main sequence stars. To investigate this further we map the large scale brightness and magnetic fields of two 10 Myr old M-type stars, and analyse other activity indicators present in their spectra. We also analyse the radial velocity (RV) variations of each star, using the brightness map information to characterise stellar jitter in the RV curves, allowing us to explore any underlying RV signals due to the presence of young exoplanets.

4:45 –5:00 p.m. — Luminous red novae: population models and future prospects
George HOWITT, PhD student, University of Melbourne

The recent discovery of gravitational waves from merging compact object binaries has highlighted the importance of understanding how these systems form. Luminous red novae - a class of moderately bright optical transients with a plateaued light curve similar to type-IIP supernovae - are potentially a signature of common-envelope evolution, an important channel for the formation of compact object binaries. Using binary population synthesis simulations together with a model of the light curve, we predict detection rates of luminous red novae with the LSST, as well as the expected distribution of plateau luminosities and durations.

Slides (PDF file) (1.3 MB).

5:00 –5:15 p.m. — Modelling single star evolution in Globular Clusters
Poojan AGRAWAL, PhD student, Swinburne University of Technology

Globular clusters are crucial for understanding stellar properties like chemical abundances, stellar kinematics and for constraining stellar populations especially binaries which are important sources of Gravitational Waves. We intend to improve the treatment of stellar evolution in the NBODY6 code (Aarseth 2003) for globular cluster modelling which currently uses SSE (Single Star Evolution, Hurley et al. 2000)--based on polynomial fits to stellar tracks--for this purpose. As an alternative, we incorporate flexible stellar evolution based on direct interpolation of the MIST (MESA Isochrone and Stellar Track, Choi et al. 2016) stellar tracks. This allows us to study the evolution of massive stars in globular clusters with a broad range of metallicities and rotation rates.

Slides (PDF file) (3.9 MB).

5:15 –5:30 p.m. — Using solar twins to constrain variation in the fine-structure constant on the Galactic scale
Daniel Andrew BERKE, PhD student, Swinburne University of Technology

The fundamental constants of nature are assumbed to be the same at all times and locations, but as their values cannot be calculated directly this remains an assumption. The fine-structure constant (commonly denoted alpha) which characterizes the strength of electromagnetism has been tested at various scales ranging from the Earth's surface to high-redshift quasar absorption systems but has seldom been tested on the Galactic scale. Various speculative extensions to the Standard Model include predictions that alpha may change based on the background density of dark matter, which would not appear as readily in searches on other scales. I will present an approach that involves using solar twins (stars very similar to the Sun) as sensitive probes of the value of alpha throughout the Galaxy. The methodology is based on the well-tested many-multiplet method and has the potential to constrain alpha at the level of a few parts per billion.

Slides (PDF file) (12.2 MB).

Special session: SKA precursor science with ASKAP and MWA 2

Location: ATC 101 — Chair: Shivani BHANDARI, CSIRO/ATNF

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — WALLABY early science - Imaging of a nearby spiral galaxy
Dane KLEINER, Postdoctoral Fellow, CSIRO

WALLABY is the main extragalactic, wide-field HI survey that will be observed with ASKAP. Its primary aim is to examine the HI properties and large-scale distribution of up to 500'000 galaxies out to a redshift of z=0.26. I will present the progress of WALLABY early science including: Images of the nearby, gas-rich, spiral galaxy IC 5201 and 3 gas-rich dwarf satellite galaxies, revealed through multi-epoch data combination. This process has enabled us to reach the sensitivity of the full WALLABY survey. I will also give an update on the progress of ASKAP and its journey towards being fully operational.

Slides (PDF file) (17.9 MB).

4:15 –4:30 p.m. — Gemini Follow-up of Two Massive HI Clouds Discovered with the Australian Square Kilometer Array Pathfinder
Juan MADRID, Postdoctoral Fellow, CSIRO

Using the Gemini Multi Object Spectrograph (GMOS) we search for optical counterparts of two massive (~10^9 solar masses) neutral hydrogen clouds near the spiral galaxy IC 5270, located in the outskirts of the IC 1459 group. These two HI clouds were recently discovered using the Australian Square Kilometer Array Pathfinder (ASKAP). Two low surface brightness optical counterparts to one of these HI clouds are identified in the new Gemini data that reaches down to magnitudes of ~27.5 mag in the g-band. The observed HI mass-to-light ratio derived with these new data, M(HI)/Lg=242, is among the highest reported to date. We are also able to rule out that the two HI clouds are dwarf companions of IC 5270. Tidal interactions and ram pressure stripping are plausible explanations for the physical origin of these two clouds.

4:30 –4:45 p.m. — WALLABY Early Science observations of the NGC 7232/3 triplet
Karen LEE-WADDELL, Postdoctoral Fellow, Commonwealth Scientific and Industrial Research Organisation

Many present-day galaxies reside in group environments where tidal interactions dominate the dynamics of the contained members. Close encounters between gaseous spirals can produce transient tidal features (e.g. bridges, tails and knots) as well as long-lived tidal dwarf galaxies (TDGs) that can constrain the properties of these interaction events, thereby enabling a direct study of this evolutionary process. The extensive capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) provide wide-field observations with the sensitivity and resolution required to resolve the HI of faint and/or extended tidal features. During the Wide-field ASKAP L-band Legacy All-sky Blind surveY (WALLABY) Early Science program, ASKAP-12 was used to observe 4 spiral-rich fields to the depth of the full WALLABY survey. One of these fields is centred on NGC 7232/3, an interacting triplet located within a groups of galaxies. There is new evidence that other groups members are actively involved in the interaction and strong indications that a TDG is being formed in the process. I will present these findings as well as provide an update on the WALLABY Early Science program.

Slides (PDF file) (23.7 MB).

4:45 –5:00 p.m. — ASKAP/WALLABY Early Science Observations of the NGC 7162 Galaxy Group
Tristan REYNOLDS, PhD student, International Centre for Radio Astronomy Research/University of Western Australia

WALLABY is the all-sky HI spectral line survey on the Australian Square Kilometre Array Pathfinder (ASKAP). Prior to the full survey commencing, four early science fields have been observed for validation of the instrument and processing pipeline and to investigate HI in the group environment. I will present results of the NGC 7162 galaxy group observed as part of WALLABY early science, where I am looking for direct and indirect signs of interactions and the potential impact on the HI content in the group environment. As validation I will compare the ASKAP observations with archival data from HIPASS and the Australia Telescope Compact Array (ATCA). We are able to increase the group membership from four to six galaxies, including the first HI detection of the dwarf galaxy, AM 2159-434, providing the first redshift measurement for this galaxy.

Slides (PDF file) (18.2 MB).

5:00 –5:15 p.m. — ASKAP Wide and Deep HI surveys
Jonghwan RHEE, Research Fellow, ICRAR, UWA

Australian Square Kilometre Array Pathfinder (ASKAP) conducted its early science surveys between 2016 and 2018. During the early science commissioning, Widefield and Deep HI surveys called Widefield ASKAP L-Band Legacy All-Sky Blind Survey (WALLABY) and Deep Investigation of Neutral Gas Origin (DINGO) observed early science fields consisting of galaxy groups and clusters and redshift survey field. The ASKAP wide field-of-view (5.5 x 5.5 deg) allows us to study a group or cluster environment with a single pointing observation. However, the processing of such widefield ASKAP data is challenging. I will present the WALLABY and DINGO early science data processing and the preliminary results from one of the four Wallaby fields observed (Dorado group) as well as HI spectral stacking results for DINGO data.

Slides (PDF file) (27.6 MB).

5:15 –5:30 p.m. — Deep Low Frequency Observations of the GAMA 23 Field
Nick SEYMOUR, Faculty, ICRAR/Curtin

Radio surveys are powerful tools to trace the evolution of star forming galaxies and radio-loud active galactic nuclei across cosmic time. The new long baselines of phase 2 of the Murchison Widefield Array (MWA) decrease the confusion limit by more than an order of magnitude, thereby allowing extremely deep images of low frequency sky. I will present the first MWA deep survey which reaches $<1\,$mJy at 200\,MHz and covers $>200\,\deg^2$. We targeted the GAMA23 survey field due to the superb suite of ancillary data available (and the lack of nearby bright radio sources). I will present the properties of the host galaxies of low frequency selected galaxies including radio spectral energy distributions and a low redshift radio distribution function. I will include discussions of the science from future observations of this field at other frequencies. Furthermore, I will discuss the prospect for on-going and future deep radio surveys with the MWA.

Slides (PDF file) (20.0 MB).

Mon, 25 Jun, 6:00 p.m. to 7:30 p.m. Day ↑ | Top ↑

Evening Event: ECR Chapter Speed Meet-A-Mentor

Location: AMDC Level 3 Sky Lounge

Mon, 25 Jun, 7:30 p.m. to 9:30 p.m. Day ↑ | Top ↑

Evening Event: IDEA Chapter Rainbow Dinner

Glenferrie hotel

The Rainbow Dinner is sponsored by People & Culture at Swinburne University.


Tue, 26 Jun

8:30–9:00 a.m. | 9:00–10:15 a.m. | 10:15–10:30 a.m. | 10:30–11:00 a.m. | 11:00–11:45 a.m. | 11:45a.m.–12:15 p.m. | 12:15–12:30 p.m. | 12:30–2:00 p.m. | 2:00–3:30 p.m. | 3:30–4:00 p.m. | 4:00–5:30 p.m. | 6:00–10:00 p.m.

Tue, 26 Jun, 8:30 a.m. to 9:00 a.m. Day ↑ | Top ↑

Arrival tea/coffee

Location: ATC 101 foyer

Tue, 26 Jun, 9:00 a.m. to 10:15 a.m. Day ↑ | Top ↑

Special session: ADACS special session on a focus on big data and computing 1

Location: ATC 101 — Chair: Paul HANCOCK, Curtin University

09:00 - 10:30 Session Recording

9:00 –9:45 a.m. — ADACS Keynote Talk: Collaborations in the Extreme: 
The rise of open code development in the scientific community
Kelle CRUZ, Faculty, City University of New York Hunter College

In this lecture, I will discuss how the scientific landscape is changing as a result of the growing trend towards international, interdisciplinary, collaborative software development made possible by the internet. More than ever before, software is a key component of any scientific result, and the ability to easily share code is rapidly resulting in changing expectations around scientific reproducibility—a fundamental tenet of the scientific process. Furthermore, in this new landscape, scientific communities are developing open source software, mostly built and maintained by unpaid volunteers, upon which both scientists and industry are becoming increasingly dependent for day-to-day operations. I will briefly provide the backstory of how these shifts have come about, describe some of the most impactful open source projects — such as astropy, matplotlib, and pandas — and discuss efforts currently underway aimed at ensuring these community-led projects are supported and sustainable. I will also describe some of my personal journey which includes founding the AstroBetter Blog and Wiki, being on the Coordinating Committee of the Astropy Project, and my latest venture, starting a business called ScienceBetter Consulting, a small consulting firm with a goal of utilizing a new way to trade expertise relevant to scientific research and education. I will conclude with a discussion of the implications of the rise of open code development for science education and academic science.

9:45 –10:00 a.m. — Data Central for Survey Teams
Elizabeth MANNERING, Professional staff, Australian Astronomical Observatory

Data Central is a virtual observatory service designed for use by astronomers and survey teams. It is a central repository for data that provides long term availability, data security and IVOA compliance. We are now ready to offer new services to enable the smooth running of astronomical surveys. We introduce these services here, including: a survey team data cloud, which allows teams to move data quickly and easily from the telescope to the desktop; document central, a content management system which allows teams to produce detailed documentation for both public and private consumption; and private team data access, so that teams can query and manage data that are not yet ready for public release. We will present a case study of the DEVILS survey team, who have been running their survey through system since December 2017.

Slides (PDF file) (34.3 MB).

10:00 –10:15 a.m. — More Usable Flops per Watt: A Story About a Highly-optimized Correlation Function Code
Manodeep SINHA, Postdoctoral Fellow, Swinburne University of Technology

Galaxy clustering is determined by a combination of cosmological parameters, non-linear gravitational collapse, and the physics of galaxy formation. Consequently, comparing the the observed and predicted correlation functions provides a stringent test for galaxy formation theories as well as precise values of cosmological parameters. However, quantifying the clustering strength requires computing pair-wise separations -- an inherently quadratic process. Since large galaxy surveys, and consequently the theoretical models, contain millions of galaxies, computing the correlation function becomes a bottleneck in the analysis pipeline. With upcoming surveys like Large Synoptic Survey Telescope and the Square Kilometre Array (SKA), the number of detected sources will increase many-folds, and will exacerbate the bottleneck. I will show that software tuned to the underlying CPU hardware can speed up the calculation by almost two orders of magnitude. For modern CPUs, such a tuning involves proper utilization of the cache hierarchy, vectorized code targeting the Single Instruction Multiple Data (SIMD) capable wide vector registers as well as {\em many-core} parallelization. Here I present Corrfunc -- a suite of OpenMP-parallelized clustering codes that exploit current CPU micro-architecture with custom Advanced Vector Extensions (AVX) and Streaming SIMD Extensions (SSE) intrinsics. Corrfunc can compute a variety of correlation functions for source positions in either a Cartesian geometry (i.e., generated from cosmological simulations) or for positions on the sky. The algorithm within Corrfunc can be easily adapted to a variety of different measurements and has already been implemented for nearest neighbour searches, group finding in galaxy surveys, weak lensing measurements etc. By design, Corrfunc is highly optimized and can compute wp(rp) for O(1 million) galaxies in $\sim 6$ seconds on a post-2011 CPU, which is at least a factor of few faster than existing public correlation function routines. Corrfunc is covered by a suite of tests, extensive documentation and is publicly available at

Slides (PDF file) (1.5 MB).

Tue, 26 Jun, 10:15 a.m. to 10:30 a.m. Day ↑ | Top ↑

Poster Sparklers

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

09:00 - 10:30 Session Recording

Tue, 26 Jun, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Location: ATC 101 foyer

Tue, 26 Jun, 11:00 a.m. to 11:45 a.m. Day ↑ | Top ↑

Special session: ADACS special session on a focus on big data and computing 2

Location: ATC 101 — Chair: Paul HANCOCK, Curtin University

11:00 - 12:30 Session Recording

11:00 –11:15 a.m. — Using Extreme Digitisation to Combat Data Challenges in CMB Observations
Lennart BALKENHOL, Masters student, University of Melbourne

Observations of the Cosmic Microwave Background (CMB) are of immense value to modern cosmology. However, future CMB experiments must confront challenges in mission planning, hardware and analysis that arise from the sheer size of the time-ordered-data being recorded. These challenges are particularly significant for Antarctic and satellite experiments which depend on satellite links to transmit the data. We investigate using extreme digitisation to address these challenges. Unlike lossless compression, extreme digitisation introduces additional noise into the data. We present an optimal 3 bit digitisation scheme, and show that such a scheme’s noise penalty is very small (percent-level) for CMB power spectrum measurements. This is impressive considering that it would reduce the data volume by an order of magnitude. We argue that extreme digitisation is a promising strategy for upcoming experiments.

Slides (PDF file) (8.5 MB).

11:15 –11:30 a.m. — PerSieve: understanding the role for the astronomer in the data-intensive era
Sarah HEGARTY, PhD student, Swinburne University of Technology

As astronomy’s data-intensive era dawns, the workflows we use to make discoveries are changing dramatically. By necessity, the traditional role of the astronomer is giving way to increased automation and AI. However, we have much to gain by maintaining an active role for the astronomer in this new generation of data-intensive workflows. Accordingly, I will present PerSieve, a platform developed to enable visual assessment and analysis of data within automated pipelines. I will describe the use of PerSieve in fast transient searches with the Deeper, Wider, Faster program. Finally, I will discuss lessons learned about how astronomers work - and the implications for designing discovery workflows in the data-intensive era.

11:30 –11:45 a.m. — High-performance pipeline processing for ASKAP
Matthew WHITING, Professional staff, CSIRO

The Australian Square Kilometre Array Pathfinder (ASKAP) is a radio-synthesis telescope located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, featuring thirty-six 12m dishes equipped with Phased- Array-Feed (PAF) receivers. These provide a wide, 30 square degree instantaneous field-of-view by forming up to 36 separate dual-polarisation beams at once. This results in a high data rate: 70 TB of correlated visibilities in an 8 hour observation, which cannot be stored indefinitely - requiring high-performance calibration & imaging pipelines in order to process these data in near-real-time. The ASKAPsoft package has been developed specifically for meeting this challenging problem. Particular design decisions in the imaging algorithms, and the framework under which they run, have been made to meet processing requirements on memory and run-time, and scientific requirements.

Tue, 26 Jun, 11:45 a.m. to 12:15 p.m. Day ↑ | Top ↑

Louise Webster Prize Talk

Location: ATC 101 — Chair: Stuart WYITHE, University of Melbourne

11:00 - 12:30 Session Recording

11:45 a.m. –12:15 p.m. — The cosmic evolution of Ionised gas kinematics
Emily WISNIOSKI, Postdoctoral Fellow, Australian National University

The depth of the KMOS3D Survey has allowed us to study in unprecedented detail rare galaxies at z>1 that are likely in the process of quenching. The short timescales associated with the quenching process make it difficult to catch galaxies “in the act” of shutting down their star formation. Compact star-forming galaxies, making-up ~7% of our sample, are selected to have properties aligned with already quenched galaxies at the same or lower redshifts but forming stars at rates 2-10x higher. We measure resolved kinematics of ~30 of these galaxies within the KMOS3D survey. Our results - the first resolved spectral data of such objects - show that compact star-forming galaxies are rotationally-dominated systems, providing strong evidence that recently quenched galaxies at these epochs are likely to be “fast rotators” . The majority of compact star-forming galaxies show evidence of low molecular gas fractions from ALMA observations and nuclear activity indicative of secular quenching processes that may retain the rotation observed in the star-forming phase. The KMOS3D survey, an integral field survey of over 600 galaxies at z=0.7-2.7 using KMOS at the VLT, will make their data public this year. In addition to the above science (Wisnioski et al. 2018) I will describe the survey and data products that will soon be available to the Australian community.

Tue, 26 Jun, 12:15 p.m. to 12:30 p.m. Day ↑ | Top ↑

Poster Sparklers

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

11:00 - 12:30 Session Recording

Tue, 26 Jun, 12:30 p.m. to 2:00 p.m. Day ↑ | Top ↑


Location: ATC 101 foyer

IDEA Chapter Town Hall Meeting

Location: ATC 101

Tue, 26 Jun, 2:00 p.m. to 3:30 p.m. Day ↑ | Top ↑

Special session: Massively multiplexed spectroscopic surveys 1

Location: ATC 101 — Chair: Emily WISNIOSKI, Australian National University

14:30 - 15:30 Session Recording

2:00 –2:15 p.m. — TAIPAN and the Starbug Fibre-Positioning Technology
Kyler KUEHN, Professional staff, Australian Astronomical Observatory

The TAIPAN instrument -- the first in the world to use the Starbug robotic fibre-positioning technology -- is now beginning operation on the 1.2m UK Schmidt Telescope at Siding Spring Observatory. We describe the design of the instrument, and especially how it makes use of Starbugs for efficient multi-object spectroscopic observation. We describe the science that TAIPAN enables, and we look to the future of Starbugs, from the TAIPAN-300 upgrade to the MANIFEST facility on the Giant Magellan Telescope.

2:15 –2:30 p.m. — Update on the Giant Magellan Telescope project
Sarah BROUGH, Faculty, UNSW

I will provide an update on the Giant Magellan Telescope (GMT) project, which is now embarked on its construction phase at Las Campanas Observatory in Chile. There have been significant advances in the project over the last year, including progress on the primary mirrors, the awarding of the main telescope mount tender and the start of hard-rock excavation. I will report progress with the two instruments that Australia will be building for the GMT, the GMTIFS AO imager and integral field spectrograph and the MANIFEST fibre feed system. I will also discuss challenges the GMT project faces.

Slides (PDF file) (8.6 MB).

2:30 –2:45 p.m. — Future Prospects for the Maunakea Spectroscopic Explorer
Aaron ROBOTHAM, Faculty, International Centre for Radio Astronomy Research / UWA

The Maunakea Spectroscopic Explorer (MSE) project will transform the CFHT 3.6m optical telescope into a 10m class dedicated multi-object spectroscopic facility, with an ability to simultaneously measure thousands of objects with a spectral resolution range spanning 2,000 to 20,000. The project is currently in design phase, with full science operations nominally resuming in 2025. There is currently a big push to update the science case with the creation of two or more science reference surveys. As Australia is one of the long-standing project partners, Australian researchers are being invited to contribute to this process. In this talk I will summarise the project progress to date, the current scientific capabilities of the planned telescope, and the future possibilities for Australia to engage in this project as a funding partner.

2:45 –3:00 p.m. — The Taipan Peculiar Velocity Survey
Khaled SAID, Postdoctoral Fellow, Research School of Astronomy & Astrophysics, Australian National University.

Taipan is a multi-object spectroscopic galaxy survey that will cover the whole southern sky and measure redshifts for two million galaxies and peculiar velocities for 100k galaxies in the local universe. It will use the refurbished 1.2m UK Schmidt telescope with an innovative “starbugs” optical fibre positioner and a purpose-built spectrograph.Expected results from Taipan include the most accurate measurements of the present-day expansion rate of the universe (the Hubble constant) to 1\% precision, the creation of the largest maps of density and velocity field of the nearby universe, and the growth rate of structure to 5\%. Measurements of peculiar velocities will be based on the Fundamental Plane distance indicator technique for early-type galaxies. Accurate peculiar velocity data will significantly improve our understanding of the observed dipole in the Cosmic Microwave Background, enable sensitive tests of gravitational physics as well as minimizing the uncertainty of the gravitational wave measurement of $H_0$. The growth rate of cosmic structure will be measured through two independent and complementary methods: (i) the FP based peculiar velocities, and (ii) the effect of redshift-space distortion. These two methods complement each other because redshift-space distortion measurements are sensitive to scales of tens of Mpc, while peculiar velocity measurements can reach scales of hundreds of Mpc.

Slides (PDF file) (18.4 MB).

3:00 –3:15 p.m. — The Drivers of Stellar Populations in Early-type Galaxies
Tania BARONE, PhD student, Australian National University

The well-established correlations between the mass of a galaxy and the properties of its stars are considered evidence for mass driving the evolution of the stellar population. However, for our sample of 625 early-type galaxies (ETGs) with integral-field spectroscopy from the SAMI Galaxy Survey, compared to correlations with mass, the color—gravitational potential ($\Phi$), [Z/H]--$\Phi$, and age—surface density ($\Sigma$) relations show both smaller scatter and less residual trend with galaxy size. These results lead us to the following inferences: (1) the color--$\Phi$ diagram is a more precise tool for determining the developmental stage of the stellar population than the conventional color--$M$ diagram; and (2) gravitational potential is the primary regulator of global stellar metallicity, via its relation to the gas escape velocity.

Slides (PDF file) (2.9 MB).

3:15 –3:30 p.m. — Impact of group environment on galaxy star formation in GAMA
Stefania BARSANTI, PhD student, Macquarie University

It is well established that cluster galaxies show a suppression of star formation with respect to the field, but the situation is less clear for galaxies in groups. We studied 1197 Galaxy And Mass Assembly (GAMA) galaxy groups to explore whether and how the group environment may affect the star formation properties of infalling star-forming galaxies. We analysed the projected phase space in the low-mass halo regime, observing that the fraction of star-forming members is higher in the regions dominated by recently accreted galaxies, whereas passive galaxies dominate the virialised regions. We also observe a small decline in specific star formation rate of star-forming galaxies towards the group centre by a factor ∼1.2 with respect to field galaxies. Similar to cluster studies, we conclude that star-forming group galaxies represent an infalling population from the field to the halo and show suppressed star formation. Our results have been published by The Astrophysical Journal in Barsanti et al. (2018).

Special session: SKA precursor science with ASKAP and MWA 3

Location: EN 101 — Chair: Keith BANNISTER, Australia Telescope National Facility

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — Square Kilometre Array update
David LUCHETTI, Other, Mr

The international Square Kilometre Array Project (SKA) is working towards building the SKA1_Low telescope in Australia and SKA1_Mid in South Africa. Later this year, the SKA partners plan to sign a treaty that will establish an intergovernmental organisation, ready for construction of the telescopes. In parallel, the telescope designs are being finalised by international engineering consortia, with the system Critical Design Review scheduled for early 2019.

Douglas Bock, Australian Science Director, SKA Organisation; David Luchetti, Australian SKA Director, Department of Industry, Innovation and Science

2:15 –2:30 p.m. — ASKAP commissioning and survey science update
Aidan HOTAN, Research Fellow, CSIRO

The Australian SKA Pathfinder is CSIRO Astronomy and Space Science's latest radio telescope and the newest addition to the Australia Telescope National Facility. Using Phased Array Feed technology, ASKAP will have a 30 square degree field of view, allowing it to rapidly survey the sky at frequencies between 700-1800 MHz. Construction is due for completion this year and we have been operating in early science mode with 1/3 of the full system since late 2016. This talk describes the status of the construction and commissioning project and outlines the process by which we intend to scale up towards large-scale surveys with the full complement of hardware in 2019.

Slides (PDF file) (996.9 KB).

2:30 –2:45 p.m. — Low-frequency polarimetry on the path to the SKA: the POGS project
Christopher RISELEY, Postdoctoral Fellow, CSIRO Astronomy & Space Science

Investigating the origin of cosmic magnetic fields is a key science driver behind the Square Kilometre Array (SKA). With the typical sensitivity predicted for surveys with the SKA, we expect to use linearly-polarized sources to statistically probe magnetic fields in the Universe, via a grid of rotation measures (RMs). Historically, the majority of large polarimetric surveys have been performed in the 21cm band, with poor frequency sampling and limited sensitivity, dramatically hindering the accuracy with which RMs can be recovered. In the current era of the SKA precursors, however, observers have access to low-frequency instruments that are both highly sensitive and possess large fractional bandwidth, enabling high Faraday-space precision. However, the large data rates involved with full polarimetric processing make such studies technically challenging, and necessitate the kind of high-performance computing resources that are crucial for fully exploiting the SKA’s scientific potential. In this talk, I will present the latest results from the POlarization from the GLEAM Survey (POGS) project. This is an ongoing effort to exploit the excellent sky coverage and unparalleled fractional bandwidth of the Galactic and Extragalactic All-sky MWA (GLEAM) survey to extract a catalog of sources that are linearly-polarized at low frequencies. I will present the largest of polarized sources detected in the Southern radio sky at 200 MHz, including measured Faraday depths, polarization properties, and an investigation of the nature of these sources.

Slides (PDF file) (16.1 MB).

2:45 –3:00 p.m. — The MWA GLEAM 4-Jy Sample
Sarah WHITE, Postdoctoral Fellow, Curtin University

Powerful radio-galaxies feature heavily in our understanding of galaxy evolution. However, when it comes to studying their properties as a function of redshift and/or environment, the most-detailed studies tend to be limited by small-number statistics. In this talk, I will present a new sample of nearly 2,000 of the brightest radio-sources in the southern hemisphere (Dec. < 30 deg). These were observed at low radio-frequencies as part of the GaLactic and Extragalactic All-sky MWA (GLEAM) survey, which is a continuum survey conducted using the Murchison Widefield Array (MWA). This instrument is the precursor telescope for the low-frequency component of the Square Kilometre Array, and allows us to select radio galaxies in an orientation-independent way (i.e. minimising the bias caused by Doppler boosting, inherent in high-frequency surveys). Being brighter than 4 Jy at 151 MHz, we refer to these objects as “the MWA GLEAM 4-Jy Sample”. Thanks to the location of the MWA in a protected, radio-quiet zone, we have excellent spectral coverage for these sources, with 20 radio flux-densities spanning a frequency range of 72-231 MHz. We then use multi-wavelength data -- such as existing optical spectra from the 6-degree Field Galaxy Survey (6dFGS) and mid-infrared images from the Widefield Infrared Survey Explorer (WISE) -- to identify the host galaxies of the low-frequency radio emission. With 10 times as many sources as the most-prominent, low-frequency radio-source sample that is optically complete (the revised Third Cambridge Catalogue of Radio Sources; 3CRR), the MWA GLEAM 4-Jy Sample will allow models of powerful active galactic nuclei to be tested more robustly.

Slides (PDF file) (19.3 MB).

3:00 –3:15 p.m. — Evolutionary Map of the Universe Early Science Results
Andrew O'BRIEN, PhD student, CSIRO

We present several exciting EMU results obtained through the ASKAP Early Science Program. New images of the Galactic plane and Magellanic Clouds have revealed several previously undiscovered supernova remnants and planetary nebulae. Deep images of extragalactic fields, deeper and wider than any previously available images, have enabled the measurement of correlations between radio star formation rates and their host optical and infrared properties. We are also building up a 2000 sq deg image of the DES deep field to commission the EMU cosmology pipeline. These results demonstrate the enormous capabilities of ASKAP, even though it's still in its commissioning stage, and indicate the enormous potential for continuum science once the full instrument is available.

3:15 –3:30 p.m. — Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex
Chenoa TREMBLAY, PhD student, ICRAR-Curtin University

Since their discovery in the 1980s, recombination lines have been used as an important probe of interstellar and intergalactic gas. Carbon recombination lines, detected at low radio frequencies, are atoms the size of viruses making them sensitive probes of the diffuse cold neutral medium. By observing between 100 and 150MHz, we can study the interface between the radiation mechanism transition from collisional pumped to radiatively pumped within the HII regions. In this talk, I will present the first results from the carbon recombination line survey toward the Orion Molecular Cloud complex at low frequencies with the Murchison Widefield Array.

Tue, 26 Jun, 3:30 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

Location: ATC 101 foyer

Tue, 26 Jun, 4:00 p.m. to 5:30 p.m. Day ↑ | Top ↑

Special session: Massively multiplexed spectroscopic surveys 2

Location: ATC 101 — Chair: Stefania BARSANTI, Macquarie University

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — Opportunities for Australia with the Large Synoptic Survey Telescope
Sarah BROUGH, Faculty, UNSW

The Large Synoptic Survey Telescope (LSST) is currently under construction. This 8m telescope will start a deep-wide-fast imaging survey of the whole Southern hemisphere in the early 2020s - bringing optical astronomy into the Petascale Data Era. In this talk I will introduce LSST and give an update on its progress. I will also discuss the extensive scientific opportunities available for Australia with this next generation survey.

Slides (PDF file) (9.3 MB).

4:15 –4:30 p.m. — The transformation of satellites galaxies in groups as seen by SAMI
Luca CORTESE, Faculty, International Centre for Radio Astronomy Research - University of Western Australia

Understanding how environment affects galaxy formation and evolution remains one of the most outstanding challenges in extragalactic astronomy. We know that bulge-dominated and quiescent galaxies are more frequent in groups and clusters, but does this really mean that a galaxy becoming a satellite always experiences two types of transformation: i.e., quenching and change of structure? If so, do they happen on the same time-scales? Or rather, is there one type of transformation more efficient than the other? Until recently, addressing this issue was impossible due to the lack of observational data allowing to trace variation in star formation and changes in structures independently. Thanks to integral field spectroscopy surveys - such as SAMI - we can finally start revealing the physics of galaxy transformation. In this talk, I will present recent progress in our understanding of the physical processes driving the transformation, with particular focus on the relative importance of quenching and structural changes in the evolution of satellite galaxies. I will highlight the significant contribution that a survey like SAMI is providing to the field and discuss how next-generations IFS surveys are needed to properly unveil the complex role played by the large scale structure in shaping the Hubble sequence.

Slides (PDF file) (32.6 MB).

4:30 –4:45 p.m. — A unified understanding of scaling relations through kinematic decomposition of bulges and disks.
Sree OH, Postdoctoral Fellow, The Australian National University

We aim to quantitatively understand the distribution of angular momentum and scaling relations from the decomposition of (pressure-supported) bulge and (rotationally-supported) disk components. For the SAMI integral field spectroscopy data, we untangle bulge and disk kinematics using pPXF with the predefined weights of components from photometric bulge/disk decomposition. Based on the 2-d kinematic maps of bulges and disks, we investigate the distribution of V/σ (or λ_R) for galaxies, bulges, and disks. Looking further ahead, we explore the Tully-Fisher relation and Fundamental Plane for disk and bulge components, respectively, and seek to develop a unified understanding of galaxy dynamics and scaling relations.

Slides (PDF file) (3.6 MB).

4:45 –5:00 p.m. — The SAMI Galaxy Survey: Second Public Data Release
Nic SCOTT, Research Fellow, The University of Sydney

The SAMI Galaxy Survey has obtained spatially resolved spectroscopy of more than 2000 nearby galaxies. These data have enabled a wealth of science covering gas accretion, active-galactic nuclei, galaxy dynamics and much much more. The data are so information-rich that we, the survey team, simply can't do all the science enabled by these observations, so we're making the data public. In this talk I will briefly describe the current state of the survey and some recent science highlights on the connection between galaxy dynamics and stellar populations. I will then focus on the SAMI Galaxy Survey Second Public Data release, the new data and data products we're making available, and how YOU might be able to take advantage of all this data.

Slides (PDF file) (5.3 MB).

5:00 –5:15 p.m. — Spatially-resolved galaxy angular momentum
Sarah SWEET, Postdoctoral Fellow, Swinburne University of Technology

Specific angular momentum (j) is a fundamental parameter in the evolution of galaxies, because it traces the tidal torques experienced during their lifetimes. Gravitational torques due to interactions with neighbours in a dense environment can cause tidal stripping, removing outer, high-j material, while feedback due to AGN or stellar winds can remove inner, low-j material. Galaxy specific angular momentum is also related to its morphology. The distribution of j is different for disks and classical bulges; disks are expected to be dominated by rapidly-rotating material, while bulges have little or no ordered rotation, Gaussian-smeared by random motions. The distribution of specific angular momentum PDF(j) therefore has two-fold utility: (1) comparison against model PDF(j) indicates the relative importance of feedback vs. tidal stripping; (2) the two-function fit can be used as a kinematic thin-disk decomposition. I will illustrate how the PDF(j) can inform us of a galaxy's morphology and evolutionary history with a spanning set of examples from present-day, cosmic-noon (z=1.5) and cosmic-noon analogue galaxies.

Slides (PDF file) (5.5 MB).

5:15 –5:30 p.m. — Chasing the bright end of the z ~ 9-10 galaxy luminosity function with the BoRG
Stephanie BERNARD, PhD student, University of Melbourne

Since 2010, the Wide Field Camera 3 on the Hubble Space telescope has enabled the discovery of thousands of galaxies during the epoch of reionisation (z > 6), with several dozen candidates at the highest redshift frontier, z ~ 9-11, when the Universe was only 500 million years old. Spectroscopic observations have also begun to confirm a small handful of galaxies at z > 7, in particular the surprising confirmation of a bright H = 26.0 galaxy, GN-z11, at z = 11.1. Determining the properties of these galaxies is still a challenging endeavour, even with the help of Hubble, but with the use of multi-observatory follow-up observations from the Spitzer Space Telescope and the MOSFIRE spectrograph on Keck, we are beginning to uncover their properties. I will present follow-up efforts using multiple facilities to confirm candidates from the z ~ 9-10 Brightest of Reionising Galaxies survey, a wide-area, pure-parallel survey using Hubble/WFC3 designed to detect the brightest (H ~ 25-26) galaxies at z ~ 9-10. I will also present our newest determination of the bright end of the UV galaxy luminosity function at z > 8 using these observations, and discuss the implications on reionisation. I will also discuss prospects using JWST to explore this frontier.

Special session: SKA precursor science with ASKAP and MWA 4

Location: EN 101 — Chair: Bradley MEYERS, ICRAR/Curtin University

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — The Spectrum of Fast Radio Burst Emission
Jean-Pierre MACQUART, Faculty, Curtin University

One of the most engaging puzzles of the emission of Fast Radio Bursts (FRBs) is their extremely high inferred luminosity and burst energies; many bursts exceed energies of 10^35 J in the radio band alone. In this talk I will discuss the spectral properties of Fast Radio Bursts as a clue to the origin of their emission. In particular, I will discuss the results of attempts to detect ASKAP FRBs at low frequencies using concurrently with the MWA. I will also discuss their spectral properties at cm wavelengths: the ASKAP detections reveal that the spectrum is highly patchy, with excursions an order of magnitude above the mean signal strength. I will discuss the extent to which such behaviour can be explained by scintillation effects, or must be an intrinsic property of FRB emission.

4:15 –4:30 p.m. — The ASKAP fast radio burst project: status and plans
Keith BANNISTER, Faculty, Australia Telescope National Facility

The Australian Square Kilometer Array Pathfinder (ASKAP) has now discovered over 20 fast radio bursts in a fly's-eye mode, yielding ~10arcminute localisations. I will describe the current instrumentation and include progress towards arcsecond, interferometric FRB localisations. I will also describe plans for upgrades of the instrumentation to improve the detection rate by around factor of 30, and the sensitivity to very high dispersion measures.

4:30 –4:45 p.m. — The fast radio burst population observed by ASKAP
Ryan SHANNON, Research Fellow, Swinburne University

The fast radio burst (FRB) phenomenon has the potential to be a revolutionary astrophysical tool. The bursts show the effects of propagation through large columns of ionized plasma, which is a hallmark of passage through diffuse intergalactic media, denser media in host galaxies or both. The discovery of repeating bursts from one source, and its subsequent localization to a dwarf galaxy at a distance of 3.7 billion light years, confirmed that the population is located at cosmological distances. However, the nature of the emission remains elusive. In this talk, we will present the discovery of more than 20 FRBs in the first controlled wide-field survey, conducted with the Australian Square Kilometre Array Pathfinder. The sample includes both the nearest and the most energetic events detected to date. None of the FRBs has been found to repeat in 12,000 hours of total follow up time. This survey has determined the properties of the high-fluence population, demonstrating that these are the nearby analogues of the more distant events detected in more sensitive, narrow-field surveys. The cosmological distance scale, and similarity to the fainter sources indicate that FRB population is evolving over cosmic time and has a broad luminosity distribution that spans at least a factor of 1000. Thus fast radio bursts are detectable at high redshift (z > 5) and can probe the reionization history of the Universe.

4:45 –5:00 p.m. — CRAFT-GP:The Longest Galactic Plane Survey for Radio Transients
Hao QIU, PhD student, University of Sydney

The aim of the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey is to discover and localize fast radio transient events such as fast radio bursts (FRBs) using the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. In the past year CRAFT has discovered a number of FRBs with arcminute level localisation (Shannon et al. in prep, Bannister et al. 2017). While ASKAP has proven to be an effective instrument for finding FRBs, the same modes are capable of finding Galactic fast transients. // In this talk we present our results from the longest Galactic plane survey for single pulse transient events. With its wide field of view, ASKAP is capable of observing the galactic plane 400 times more efficiently than previous pulsar searches, enabling a survey for rare-but-bright bursts, that would have been impossible to detect otherwise. This enables us to study and characterize the most extreme forms of galactic neutron star emission, search for new classes of galactic fast transients, and determine the connection between Galactic neutron stars and FRBs. The survey has a total observation time of 10 hrs per pointing and a total sky coverage of 4800 deg$^2$ in 1.2 ms time resolution at 1.4 GHz. We have performed a large-scale search for dispersed single pulse events, repeating bursts and periodical events. We present our preliminary results for giant pulses, RRAT burst rates and the search for FRBs, slow pulsars and other transient events.

5:00 –5:15 p.m. — Early science results from the ASKAP-FLASH survey
Elizabeth MAHONY, Research Fellow, CSIRO Astronomy and Space Science

Detections of HI in absorption towards distant radio galaxies can provide a powerful tool in understanding the role that cold gas plays in the formation and evolution of galaxies. The First Large Absorption-line Survey for HI (FLASH) takes advantage of the wide bandwidth, frequency range and radio-quiet site of the Australian Square Kilometre Array Pathfinder (ASKAP) to search for HI out to redshifts of z=1, a parameter space which has been poorly explored until now. Using commissioning and early science observations the FLASH team have discovered a number of new detections of HI absorption, providing valuable insight into the types of objects we expect to detect in the full survey and allowing us to place constraints on the average HI properties at intermediate redshifts. In this talk I will give an overview of the FLASH survey and present some of our key early science results.

Slides (PDF file) (8.1 MB).

5:15 –5:30 p.m. — The Australian SKA pathfinder: Exploring the transient radio Universe.
Shivani BHANDARI, Postdoctoral Fellow, CSIRO/ATNF

We have conducted a pilot survey to search for variable and transient sources at 1.4 GHz using the Early Science data from ASKAP. The search was performed in a 30 sq. deg area centred on the NGC 7232 galaxy group over 8 epochs and observed with a near-daily cadence. Our search resulted in the detection of nine variable sources, varying on the timescales of a day and consistent with the refractive scintillation of an AGN. We also discovered a highly variable source over a time interval of a decade between the Sydney University Molonglo Sky Survey (SUMSS) and our latest ASKAP observations. We find the source to be consistent with the properties of long-term variability of a quasar. In this talk, I will present these detections and also show that the transient upper limits obtained from our pilot survey are already competitive with previous surveys, suggesting the final implementation of the ASKAP will be probing a new phase space for transients.

Slides (PDF file) (5.2 MB).

Tue, 26 Jun, 6:00 p.m. to 10:00 p.m. Day ↑ | Top ↑

ADACS Astropy And Astro Coding Chat

ATC 205

ADACS is sponsoring this informal meet-up and networking session for astro coders to help us better understand who is involved in this space and how we can support you. 

Kelle Cruz, our invited keynote speaker for the data and computing session at the ASA annual meeting, is particularly interested to meet people who extensively use astropy. If you would like to know more about how to get involved with the open source and open development astropy project do come along to chat. 

ADACS will be sponsoring pizza and drinks for this event. Please RSVP here, or contact us for more information.

Social Outing to MBO

6:00 p.m. – 10:00 p.m.

A social outing is being organised to the Mount Burnett Observatory (MBO) on Tuesday, 26 June. MBO is a community astronomical facility in the Dandenong Ranges, east of Melbourne. The association is running both optical and radio facilities, is involved with astrophotography and augmented reality experimentation, so there will be lots ...

More info →

Wed, 27 Jun

8:00–9:00 a.m. | 9:00–10:30 a.m. | 10:30–11:00 a.m. | 11:00a.m.–12:30 p.m. | 12:30–2:00 p.m. | 2:00–3:30 p.m. | 3:30–4:00 p.m. | 4:00–5:30 p.m. | 5:45–6:45 p.m. | 7:00–8:30 p.m.

Wed, 27 Jun, 8:00 a.m. to 9:00 a.m. Day ↑ | Top ↑

Heads of Departments Meeting

Location: AR 209 (staff room)

Arrival tea/coffee

Location: ATC 101 foyer

Wed, 27 Jun, 9:00 a.m. to 10:30 a.m. Day ↑ | Top ↑

Special session: ESO

Location: ATC 101 — Chair: Karl GLAZEBROOK, Swinburne

09:00 - 10:30 Session Recording

9:00 –9:30 a.m. — ESO in 2018
Rob IVISON, Faculty, ESO

The European Southern Observatory (ESO) is conducting an ambitious programme, building and operating world-class astronomical observatories on the ground and fostering cooperation in astronomy, now in partnership with the Australian community.  In this presentation I will provide an update on recent progress in the various ESO programmes, focusing mainly on the La Silla Paranal observatory and its instrumentation programme, and on opportunities for Australian participation in ESO’s vibrant science community.

9:30 –9:45 a.m. — ESO: strategic partnership and full membership
Matthew COLLESS, Faculty, ANU

I will provide an overview of the current status of Australia's strategic partnership from an ESO Council perspective, and review the necessary and sufficient conditions for Australia to achieve full membership of ESO.

9:45 –10:00 a.m. — Paranal and La Silla Update and Opportunities
Michael IRELAND, Faculty, Australian National University

Australia's strategic partnership with ESO brings with it many opportunities, with the La Silla and Paranal combining to have the world's most competitive and diverse array of instrumentation. As Australia's Scientific and Technical Committee representative, I will update the community on the capabilities of the instrumentation at these observatories, what is likely to change in the near future, and science plus instrumentation opportunities for Australia.

10:00 –10:15 a.m. — Update from your ESO Users Committee Representative
Caroline FOSTER, Research Fellow, The University of Sydney

I will give an informal update on the outcomes of the ESO Users Committee meeting on April 26-27. Particular focus will be on issued raised within the Australian community.

Slides (PDF file) (3.2 MB).

10:15 –10:30 a.m. — MAVIS: An Australian-led MCAO-Assisted Visible Imager and Spectrograph for the Very Large Telescope
Richard MCDERMID, Faculty, Macquarie University

High-performing deformable secondary mirrors, and powerful, robust sodium lasers guide stars are becoming standard technology on the world’s largest telescopes. This is enabling a new level of reliability, sky coverage, and precision for adaptive optics (AO), with multiple configuration options for different science applications. In particular, wide field, high-strehl AO performance has been demonstrated at infrared wavelengths through the use of Multi-Conjugate Adaptive Optics (MCAO). The high actuator density possible with deformable secondary mirrors is also enabling diffraction-limited performance at optical wavelengths, as demonstrated by recent observations at various 8m-class telescopes. MAVIS proposes to combine these two developments, exploiting the full capabilities of the European Southern Observatory’s 4-laser guide star Adaptive Optics Facility, providing near-diffraction limited spatial resolution of an 8m telescope across a relatively large field of view. This Australian-led instrument will provide HST-like (or better) resolution from the ground, but with the light-gathering power of the Very Large Telescope (VLT), making it a powerful complement to future facilities like the space-based JWST and the 30-40m class ground-based telescopes currently under construction. I will present an overview of the foreseen MAVIS technical and scientific capabilities, and describe ways in which you can get involved in developing the science case for this exciting new instrument.

Slides (PDF file) (4.1 MB).

Wed, 27 Jun, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Location: ATC 101 foyer

Wed, 27 Jun, 11:00 a.m. to 12:30 p.m. Day ↑ | Top ↑

Wed, 27 Jun, 12:30 p.m. to 2:00 p.m. Day ↑ | Top ↑


Location: ATC 101 foyer

ANITA Chapter Town Hall Meeting

Location: ATC 101

Australia and eROSITA Meeting: strengthening the partnership

Location: EN 101

Wed, 27 Jun, 2:00 p.m. to 3:30 p.m. Day ↑ | Top ↑

General session: Extragalactic astronomy 1

Location: ATC 101 — Chair: Simon MUTCH, The University of Melbourne

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — The mass dependance of Dark Matter Halo shapes and implications for cusps, cores and ultra diffuse galaxies
Chris BROOK, Research Fellow, Universidad de La Laguna/Instituto de Astrofisica de Canarias

Using simulations and analytic arguments, we find a significant mass dependence on how dark matter halos respond to baryons. We identify a particular mass where cores are most likely to occur due to feedback effects on the gravitation potential. We then provide a mass dependent density profile analogous to the NFW profile, and test our theoretical predictions against the rotation curve data of galaxies that span a wide range of mass. The physical mechanisms that drive an expansion of dark matter in the central regions of galaxies of a certain mass can also affect the distribution of stars, and we invoke this mechanism to formulate a theory for the formation of Ultra Diffuse galaxies.

2:15 –2:30 p.m. — Resolving z ~2 galaxy using adaptive coadded source plane reconstruction
Soniya SHARMA, PhD student, Australian National University

Natural magnification provided by gravitational lensing coupled with Integral field spectrographic observations (IFS) and adaptive optics (AO) imaging techniques have become the frontier of spatially resolved studies of high redshift galaxies (z>1). Mass models of gravitational lenses hold the key for understanding the spatially resolved source–plane (unlensed) physical properties of the background lensed galaxies. Lensing mass models very sensitively control the accuracy and precision of source-plane reconstructions of the observed lensed arcs. Effective source-plane resolution defined by image-plane (observed) point spread function (PSF) makes it challenging to recover the unlensed (source-plane) surface brightness distribution. We conduct a detailed study to recover the source-plane physical properties of z=2 lensed galaxy using spatially resolved observations from two different multiple images of the lensed target. To deal with PSF’s from two data sets on different multiple images of the galaxy, we employ a forward (Source to Image) approach to merge these independent observations. Using our novel technique, we are able to present a detailed analysis of the source-plane dynamics at scales much better than previously attainable through traditional image inversion methods. Moreover, our technique is adapted to magnification, thus allowing us to achieve higher resolution in highly magnified regions of the source. We find that this lensed system is highly evident of a minor merger. In my talk, I present this case study of z=2 lensed galaxy and also discuss the applications of our algorithm to study plethora of lensed systems, which will be available through future telescopes like JWST and GMT.

2:30 –2:45 p.m. — Thin disk and spiral arm formation at high redshift
Tiantian YUAN, Research Fellow, Swinburne

Spiral arms and thin disks are prominent components of star forming galaxies in the local universe. However, as we move towards redshift 2, both of these components vanish rapidly in observations. When, how, where and why do spiral arms first form and do the formation of spiral arms mark the formation of thin disks ? I will briefly discuss our current observational and theoretical answers to this question.

2:45 –3:00 p.m. — Early Metal Pollution in the AURORA Simulations
Adam BATTEN, PhD student, Swinburne University of Technology

The distribution of metals at early times is of fundamental importance to galaxy formation, and understanding observations from 8-metre class telescopes in the era of ESO partnership. Using the coupled radiative transfer hydrodynamical simulation series AURORA, we have tracked the distribution of ionized metals for direct comparison with redshift 6 observations from MUSE. Early results will be shown connecting the potentially observable metal extent to the intrinsic properties of these simulated galaxies.

3:00 –3:15 p.m. — The stellar kinematics and star-formation histories of high-redshift galaxies with KMOS@VLT
Jon Trevor MENDEL, Postdoctoral Fellow, Australian National University

Galaxies' integrated continuum spectra provide a powerful tool with which to study their formation and evolution. While observations of stellar absorption lines have historically been limited to a handful of objects in the high-redshift Universe, thanks to KMOS@VLT we have now been able to compile a sample of nearly 50 quiescent galaxies out to z = 2 with spectra suitable to study their kinematics and stellar populations. I will highlight some of our recent results based on using galaxy kinematics to constrain the evolution of quiescent galaxies and their dark matter haloes, as well as discuss the prospects of obtaining more detailed information about their formation histories from stellar population models.

3:15 –3:30 p.m. — Numerical effects in cosmological simulations involving baryons and self-interacting dark matter
Aaron LUDLOW, Research Fellow, ICRAR UWA

N-body simulations make robust predictions for the structure of collisionless dark matter (DM) halos: their density profiles are "cuspy", approximately "universal" and follow well-defined scaling laws that reflect their unique assembly histories. Observations indicate a much broader diversity in the inferred structure of halos, which may contradict theory. If so, this could imply that DM is self-interacting, or that galaxy formation is capable of altering the structure of halos on small scales (or both). Disentangling these effects is therefore essential, and if numerical simulations are to do so a robust assessment of their predictions must be carried out. What role do numerical parameters play in establishing halo structure in self-interacting DM models or simulations incorporating baryon physics? What impact does star formation and feedback have on halo structure? Can simulations be used to make robust predictions beyond the collisionless limit? I will present a suite of simulations developed to address these questions, highlighting important difficulties that must be overcome before quantitatively meaningful predictions can be made for the asymptotic structure of halos beyond cold DM.

General session: Planetary astrophysics

Location: EN 101 — Chair: Michael IRELAND, Australian National University

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — PLATYPUS - a radio debris disk survey
Sarah MADDISON, Faculty, Swinburne University of Technology

Observations of cold, dusty debris disks around nearby stars provide crucial information about the late stages of planet formation.  The dust grains observed in these systems are produced by collisions between unseen km-sized planetesimals leftover from the planetary formation process. The PLATYPUS (PLanetesimals Around TYpical and Pre-main seqUence Stars) survey provides information on the physical and dynamical properties of the planetesimal population. Their highly destructive mutual encounters produce solids down to very small sub-micron sizes.  Combining ATCA and ALMA data allows us to determine the slope of the power-law size distribution of dust grains, q. Different collisional models predict different q-values and the PLATYPUS survey tests predictions of collisional models of planetesimals in debris disks across a range of stellar spectral types and ages.

2:15 –2:30 p.m. — Early evolution of protostellar discs
Eloise BIRCHALL, PhD student, Australian National University

Star and planet formation are intimately entwined, and it is difficult to consider one without its implications for the other. Here I will discuss the initial results of my simulations of the formation of a protostellar disc and its associated chemical and physical evolution to investigate the implications this has for the earliest stages of planet formation. Meteoritic evidence (such as high temperature inclusions) suggests certain temperature and density processing histories throughout the Sun's protostellar disc, however such environments are not typically found in observations or simulations of other discs. I use the magneto-hydrodynamic adaptive mesh refinement code FLASH to simulate the collapse of a cloud into a star and disc, and follow the path of gas throughout the disc using tracer particles to probe the disc environment. The information from the tracer particles can then be compared with what is observed and found in meteoritic data to understand the links between the earliest stages of star and planet formation.

Slides (PDF file) (4.8 MB).

2:30 –2:45 p.m. — Binary star formation, evolution of their discs and implications on planet formation.
Rajika KURUWITA, PhD student, Australian National University

In this age of Kepler we are beginning to discover many planets in binary systems, either orbiting one component in the binary or both. However, our current understanding of planet formation has focused on single stars. My work is motivated by planet and disk occurrence around binary stars. We carry out magnetohydrodynamical simulations with FLASH of the formation of a single, a tight binary (a ~2.5AU) and a wide binary star (a ~ 45AU), as well as turbulent simulations of binary star formation. We study the outflows and jets from these systems to understand the contributions the circumstellar and circumbinary discs have on the efficiency and morphology of the outflow. I will also present work on disc disruption during binary star formation and explore the implications on planet formation.

Slides (PDF file) (15.6 MB).

2:45 –3:00 p.m. — Planet or stellar variability?
Jinglin ZHAO, PhD student, The University of New South Wales

In radial velocity detection of exoplanets, it has been a great challenge to tell if an apparent radial velocity shift is caused by gravitationally bound companions (e.g. planets) or intrinsic stellar variability that deforms the spectral lines. The Fourier Transform of the line profile might be the key to solving this problem. This is because a pure shift of the line would simply change the phase angle, and the power spectrum will remain the same in the Fourier space; whereas the Fourier Transform of a deformed line profile behaves differently. I will talk about some latest results of this experiment using simulated spectral data.

3:00 –3:15 p.m. — Searching for young exoplanets with high-contrast imaging in the near-infrared
Alexander WALLACE, PhD student, Australian National University

Direct imaging of exoplanets is limited by the optics of the telescope which need to be removed by subtraction of point spread functions (PSFs.) In this project, existing methods of image analysis are tested with a large sample of young stars imaged by Keck, especially in the Taurus association, to search for companions. Additionally, I am simulating planet formation and luminosity evolution to determine the probability of planet detection with current instruments and analysis methods. I am also working on modifying our analysis methods to achieve better sensitivity limits. This will work towards improving our chances of planet detection and, in the event of any clear detections, improving our understanding of planet formation.

3:15 –3:30 p.m. — Enhanced Constraints on the Interior Composition and Structure of Rocky Exoplanets
Haiyang WANG, PhD student, Research School of Astronomy and Astrophysics, The Australian National University

This talk presents several important constraints that can reduce the uncertainty in the estimates of the interior composition and structure of rocky exoplanets. A major cause of the modelling inaccuracy is inherent in the prevalent assumption: elemental abundances of a planet are identical to the elemental abundances of its host star. Host stellar abundances are good proxies of planetary abundances, but only for refractory elements. This is particularly true for rocky planets, as evidenced by the relative composition differences between the Sun, Earth and other inner solar system bodies. We therefore argue that host stellar abundances should be devolatilised in order to correctly represent the bulk elemental composition of a rocky planet orbiting the host star. The modelling inaccuracy can be further reduced by considering light elements in the core of a rocky exoplanet. By applying these constraints to the Sun, it is shown that our estimates for the mantle and core compositions as well as core mass fraction of the Earth are verifiable by independent measurements/estimates. By applying our approach to four solar-type host stars: Kepler-10, Kepler-20, Kepler-21 and Kepler-100, we found that a potential rocky exoplanet orbiting in the habitable zone of Kepler-21 would be the most Earth-like while one orbiting Kepler-10 would be the least. To assess the likeness of a rocky exoplanet to the Earth (in terms of interior composition and structure), high-precision abundances of the host star are critical. Based on our modelling approach and proposed constraints, a typical precision better than 0.04 dex for host stellar abundances is necessary for such an assessment to be made.

Slides (PDF file) (15.3 MB).

National Committee for Astronomy (NCA)

Location: ATC 714

Please note that NCA is scheduled from 2:30 p.m to 5:30 p.m

Wed, 27 Jun, 3:30 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

ATC 101 foyer

National Committee for Astronomy (NCA)

Location: ATC 714

Please note that NCA is scheduled from 2:30 p.m to 5:30 p.m

Wed, 27 Jun, 4:00 p.m. to 5:30 p.m. Day ↑ | Top ↑

General session: Extragalactic astronomy 2

Location: ATC 101 — Chair: Barbara CATINELLA, ICRAR/UWA

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — The Connection Between Structure and Cold Gas Reservoirs in Galaxies.
Robin COOK, PhD student, International Centre for Radio Astronomy Research

There is a distinct bimodality seen in the population of galaxies in the local Universe separated between those that are dominated by central, concentrated bulges and those that are mostly disk-dominated. The fact that disk-dominated galaxies are generally actively forming stars whereas elliptical galaxies tend to be quenched has often lead to the conclusion that the presence of a bulge regulates the efficiency with which cold gas can collapse and form stars. However, a causal link is yet to be uncovered; is it true that galaxies with equivalent properties in their disks will have their cold gas reservoirs and star formation efficiencies impacted by differing contributions of a bulge component? I will attempt to quantify such questions with the unique combination of robust bulge-disk decomposition (ProFit) and observations of cold gas (xGASS) for a large, representative sample of local galaxies.

4:15 –4:30 p.m. — The Indirect Influence of Quasars on Reionization
Jacob SEILER, PhD student, Swinburne University Technology

The Epoch of Reionization represents a transition between the neutral, post-recombination Universe and the highly ionized one we observe today. The time and spatial evolution of ionized regions during reionization depends on the fraction of ionizing photons that escape their host galaxies into the intergalactic medium. This parameter, the escape fraction $f_\mathrm{esc}$, is almost wholly unconstrained with both the value and functional form remaining uncertain. A further open question focuses on the sources of reionization and whether quasars make an appreciable contribution to the number count of ionizing photons compared to star-forming galaxies. Instead of focusing on the intrinsic emission of ionizing photons from quasars, I pose an alternate question: Can quasars \textit{indirectly} influence reionization by allowing ionizing photons from galaxies to escape more easily? By evolving a galaxy population through cosmic time and adopting a model that boosts the value of $f_\mathrm{esc}$ following a quasar event, I find that the mean value of $f_\mathrm{esc}$ is greatest for intermediate mass galaxies. Such a mass dependence has consequences for the $21$cm signal; one of the most important observables associated with reionization. With current and upcoming telescopes such as the Square Kilometre Array and the Murchison Widefield Array set to measure this signal, our results present a wealth of opportunities to potentially clarify the role quasars play during the Epoch of Reionization and solve one of the most hotly debated questions within the field.

4:30 –4:45 p.m. — Selection and characterization of Lyman Continuum Galaxies
Uroš MEŠTRIĆ, PhD student, CAS

The transition of the Universe from neutral to ionized state began at z~15 and finished around z~6. This period is known as the epoch of reionization (EoR). Although great progress has been made in the last twenty years, the question of which sources are responsible for the reionization of the IGM still remains open. Current observations and models favour young star forming galaxies as the main contributors to the global emissivity of the ionizing photons. To select high redshift galaxies that are the best candidates for emitting ionizing Lyman continuum (LyC<912Å) radiation, a robust selection method is needed. We use the selection criteria for Lyman continuum galaxies (LCGs) proposed by Cooke et al (2014) in the redshift range 3<z<5. Where it is expected that many of the LCGs with expected moderate and strong LyC reside outside the standard color selection region for Lyman break galaxies (LBG). By volume and sample size this photometric research is the largest ever performed with goal to detect and characterize the population of LCGs. Data used in this work are ZFOURGE photometric catalogs of the COSMOS, CDFS and UDF fields, CLAUDS imaging and photometry of the same fields and HST imaging. I will present and briefly discuss: the sample of the individually detected LyC emitters and the upper limit on the escape fraction of LyC emission from a stacked sample of individual non detections.

4:45 –5:00 p.m. — HI Galaxies with Little Star Formation
Vaishali PARKASH, PhD student, Monash University

Why do some galaxies have high HI masses but little accompanying star formation? We have identified galaxies from the HI Parkes All-Sky Survey (HIPASS) with little or no identifiable star formation in WISE mid-infrared and GALEX UV imaging. To determine just how little star formation HI galaxies can exhibit and what is causing the truncation of star formation in these galaxies, we have obtained new integral field unit (IFU) observations with the Wide-Field Spectrograph (WiFeS) on the 2.3 m telescope at Siding Spring Observatory. Remarkably, of the 7 galaxies observed with WiFeS, we find 5 are low-ionization nuclear emission-line regions (LINERS) or active galactic nuclei (AGNs) while another is a radio AGN.

5:00 –5:15 p.m. — Cool and Close Encounters of the HI Kind
Michelle CLUVER, Faculty, Swinburne University of Technology, Centre for Astrophysics and Supercomputing

The 64-dish SKA Pathfinder, MeerKAT, will have unprecedented sensitivity to detect low column density neutral hydrogen. Although considered relatively unimportant in the baryon cycle due to its inability to survive in harsh environments, there is growing evidence that perhaps we have underestimated the utility of this tracer, particularly in group environments where neutral gas can act as a tracer of past interactions. With high column density HI informing us of how star formation proceeds in interacting environments, could low column density HI gas be just the ticket that leads us to understand the impact of environment on galaxy evolution?

Slides (PDF file) (11.0 MB).

5:15 –5:30 p.m. — The Economics of First Galaxies Growth
Alan R DUFFY, Faculty, Swinburne University of Technology

Galaxies in the early universe grow in a time of plentiful supply of gas yet internal demand never rises to match this, in economic terms the first galaxies are in a Recession. We used the DRAGONS simulations to show that these galaxies consume their reserves of molecular gas in a timescale of 300 Myr, irrespective of baryonic physics modelled. However, there exists no such simple relation for the total gas reserves in the galaxy as probed by neutral atomic hydrogen. This suggests that the bottleneck limiting the growth of early galaxies is in converting infalling gas to cold star forming gas. In other words, the basic assumption of equilibrium models of galaxy formation, that galaxies can adjust total gas consumption within a Hubble time, does not apply for the dwarf galaxies responsible for providing most UV photons to reionise the high redshift universe.

General session: High energy astrophysics 2 + Education/outreach

EN 101 — Chair: Rebecca ALLEN, Swinburne

16:00 - 17:30 Session Recording

4:10 –4:15 p.m. — Neutrino astronomy with IceCube at the South Pole
Gary HILL, Faculty, University of Adelaide

The IceCube detector at the South Pole has observed high energy neutrinos from the Universe - opening a new window for astronomy. While all high-energy neutrinos are eventually analysed to look for correlations with other observations (electromagnetic spectrum, cosmic rays and gravitational waves), a smaller number of most-interesting events have their well-resolved directions in the sky released in real-time to allow followup observations. One such event occurred in September 2017, and several followup observations revealed the existence of a known blazar from the same direction as the neutrino, which was seen to be flaring in gamma-rays at the time of the neutrino observation. We will discuss this multi-messenger approach and what these observations might reveal about the nature of high energy neutrino sources in the Universe.

4:15 –4:30 p.m. — K2 Background Survey
Ryan RIDDEN-HARPER, PhD student, Australian National University

The Kepler K2 mission has offered the unique ability to study extra-galactic transient phenomena on the scale of minutes-to-hours. K2 has observed hundreds of thousands of objects, however, for each object, there are a multitude of surrounding pixels that only see background. These background pixels offer a possibility to conduct a large area and high cadence survey for short transient events such as kilonova, GRB afterglows, and other phenomena. I will present the preliminary transients and survey limits of the K2 Background Survey.

4:30 –4:45 p.m. — New frontiers in optical fast-transient discovery
Igor ANDREONI, PhD student, Swinburne University of Technology

Optical searches for transients are usually performed with a cadence of days or even weeks, optimal to discover supernovae. Only a few programs searched for hour-timescale transients and were rarely successful due to several limitations, for example the small volume of sky observable at such high cadence. I will present the results of deep searches for minute-timescale transients using the Dark Energy Camera, a core facility of our multi-wavelength Deeper Wider Faster program. This work pioneered the exploration of a new discovery space in optical fast-transient astronomy.

Slides (PDF file) (30.0 MB).

4:45 –5:00 p.m. — My five months in industry
Caitlin ADAMS, PhD student, Ms.

Many PhD students and postdocs are considering moving out of academia and into industry. Late last year, I took five months out of my PhD to intern with a small company in Melbourne that specialises in mathematical and statistical modelling. In this talk, I will cover my experience to raise awareness about what is available outside of academia, to the bright, capable people within it. 

Slides (PDF file) (139.2 KB).

5:00 –5:15 p.m. — The Parkes Radio Telescope as a tool for STEM engagement
Jimi GREEN, Faculty, CSIRO Astronomy and Space Science

The Parkes radio telescope, known affectionately as ‘The Dish’, is located ~380 km west of Sydney, Australia, and has been in operation since 1961. It is an iconic 64-metre parabolic antenna, with receiver systems capable of observing from 700-MHz to 26 GHz with bandwidths up to several GHz, and it is part of the CSIRO Australia Telescope National Facility (ATNF). It has been the inspiration of generations of astronomers, and for more than 10 years has provided education experiences through the PULSE@Parkes programme. I will discuss the current and future plans for STEM oriented education and outreach engagement with the telescope, particularly with regards to developing technology and the forthcoming era of the Square Kilometre Array.

Slides (PDF file) (4.9 MB).

5:15 –5:30 p.m. — Studying broadband radio spectra in the classroom
Darren HAMLEY, Masters student, Willetton Senior High School/Edith Cowan University

This talk will be co-presented by Darren Hamley and Anusha Veerahoo.

ABSTRACT: Astronomy lessons in many high schools consist mostly of ‘astro trivia’. However, for students at four high schools (two in Perth and two in Sydney), this is being supplemented with the Australian Teacher Astronomy Research Program (ATARP). This is a new scheme that involves keen, young scientists in current research, through an astronomy-focused task that uses real data. The Perth-based students are studying the broadband radio spectra of over 200 galaxies, with flux-density measurements from the Murchison Widefield Array (MWA) and the Australia Telescope Compact Array (ATCA). For the majority of sources, we expect to see an inverse, linear relationship between the logarithm of the radio brightness and the logarithm of the frequency. That is, that the radio spectrum can be described using a power-law. We access the MWA data through the GaLactic and Extragalactic All-sky MWA (GLEAM) catalogue, and use the wide frequency coverage to see the effects of poorly-studied processes, where the radio spectrum takes on a more-curved appearance. If the source is fainter at low frequencies than expected (based upon a standard, power-law description), this is likely due to some of the low-frequency radio emission being absorbed by neutral gas in the galaxy. Meanwhile, a flattening of the radio spectrum at higher radio-frequencies could be due to new radio-jets emerging, boosting the signal at these frequencies. The outcome of this project is two-fold: scientific and educational. We determine the proportion of galaxies that show spectral curvature in the radio, and investigate whether sources of similar curvature have common properties. We also give gifted high-school students an experience of what it may be like to work as an astronomer.

Slides (PDF file) (31.5 MB).

National Committee for Astronomy (NCA)

Location: ATC 714

Please note that NCA is scheduled from 2:30 p.m to 5:30 p.m

Wed, 27 Jun, 5:45 p.m. to 6:45 p.m. Day ↑ | Top ↑

Evening Event: ATNF Town Hall Meeting

Location: ATC 103

Wed, 27 Jun, 7:00 p.m. to 8:30 p.m. Day ↑ | Top ↑

Harley Wood Public Lecture

7:00 p.m. – 8:30 p.m.

Oxygen: Breathing in Stars

Professor Lisa Kewley

19:00 - 21:00 Session Recording

Life as we know it requires oxygen, carbon, and nitrogen. Yet the universe began with none of these elements. The elements responsible for life were produced in the deep recesses of stars over 13 billion years of cosmic ...

More info →

Thu, 28 Jun

8:30–9:00 a.m. | 9:00–10:00 a.m. | 10:00–10:15 a.m. | 10:15–10:30 a.m. | 10:30–11:00 a.m. | 11:00–11:30 a.m. | 11:30a.m.–12:15 p.m. | 12:15–12:30 p.m. | 12:30–2:00 p.m. | 2:00–3:30 p.m. | 3:30–4:00 p.m. | 4:00–5:30 p.m. | 7:00–11:00 p.m.

Thu, 28 Jun, 8:30 a.m. to 9:00 a.m. Day ↑ | Top ↑

Arrival tea/coffee

Location: ATC 101 foyer

Thu, 28 Jun, 9:00 a.m. to 10:00 a.m. Day ↑ | Top ↑

Special session: The future of Australian optical astronomy

Location: ATC 101 — Chair: Clare MCLAUGHLIN, Department of Industry, Innovation and Science

09:00 - 10:30 Session Recording

9:00 –9:20 a.m. — The Future of Astronomical Support at the Anglo-Australian Telescope
Chris LIDMAN, Professional staff, Australian National University

At midnight on June 30, operations of the Anglo-Australian Telescope (AAT) transfers from the Australian Government to a consortium of 13 Australian universities led by the Australian National University. With this transfer, there will be significant changes in the way observing programs on the AAT are supported. Future support will rely more heavily on the expertise and experience that lies within the Australian astronomical community. In this talk, I will describe these changes, the impact these changes are likely to have on astronomers who use the AAT, and provide a long term outlook of how the AAT and more broadly Siding Spring Observatory could evolve into the future.

Slides (PDF file) (3.9 MB).

9:20 –9:40 a.m. — A new era for optical astronomical instrumentation in Australia
Michael STEEL, Faculty, Macquarie University

The Australian Astronomical Observatory is reaching the final stages of its major transition to the Research Sector. The AAT operations and staff are to be managed by ANU on behalf of a University Consortium coordinated through AAL (the subject of a companion presentation by Chris Lidman). The instrumentation capability of the AAO is transitioning to a new home with Macquarie University, and establishing a national capability for optical instrumentation in partnership with ANU and the University of Sydney. I will provide an update on the transition of the AAO instrumentation capability, its structure and goals from 1 July 2018, as well as introducing the structure and vision of the new national capability.

Slides (PDF file) (2.0 MB).

9:40 –10:00 a.m. — Discussion and Q&A - led by Chris Lidman and Michael Steele
Chris LIDMAN, Professional staff, Australian National University


Thu, 28 Jun, 10:00 a.m. to 10:15 a.m. Day ↑ | Top ↑

Poster Sparklers

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

09:00 - 10:30 Session Recording

Thu, 28 Jun, 10:15 a.m. to 10:30 a.m. Day ↑ | Top ↑

Thu, 28 Jun, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Location: ATC 101 foyer

Thu, 28 Jun, 11:00 a.m. to 11:30 a.m. Day ↑ | Top ↑

Anne Green Prize Talk

Location: ATC 101 — Chair: Stuart WYITHE, University of Melbourne

11:00 - 12:30 Session Recording

11:00 –11:30 a.m. — Cold gas and star formation in galaxies

A detailed knowledge of how gas cycles in and around galaxies, and how it depends 
on their structural and star formation properties, as well as environment, is crucial 
to understand galaxy formation and evolution. This requires sensitive surveys
of cold gas for representative samples of galaxies, able to probe the gas-poor regime. 

I will present results based on state-of-the-art cold gas surveys and spectral stacking, 
and discuss how these are shedding light on the processes that regulate the 
position of galaxies on the stellar mass-star formation plane.

Slides (PDF file) (14.0 MB).

Thu, 28 Jun, 11:30 a.m. to 12:15 p.m. Day ↑ | Top ↑

General session: Instrumentation and methods

Location: ATC 101 — Chair: Minh HUYNH, CSIRO / ICRAR

11:00 - 12:30 Session Recording

11:30 –11:45 a.m. — Dark Matter direct detection in Australia
Elisabetta BARBERIO, Professional staff, The University of Melbourne

The quest to identify the particle nature of Dark Matter requires new and innovative approaches, combining techniques and data from a range of instruments. In the last decade, there has been impressive experimental progress to detect Dark Matter interactions with normal matter, with the development of new direct detection experiments. The sensitivity of these experiments has improved tremendously and enables the construction of uniquely suited devices to solve the Dark Matter puzzle. In the Southern Hemisphere, we have a crucial advantage in the search for dark matter via direct detection. I will discuss the direct search for dark matter within the Southern Hemisphere with the SABRE and Cygnus experiments. The SABRE experiment is the first dual-sited direct detection experiment with the Southern Hemisphere experiment located in Stawell, Australia, while the Northern Hemisphere experiment will be hosted at Laboratori Nazionali del Gran Sasso, Italy. I will also discuss the physics program of the first underground physics laboratory of the Southern Hemisphere, SUPL (Stawell Underground Physics Laboratory), the first-ever integrated underground laboratory in Australia that will also host astro-biology and biology research.

11:45 a.m. –12:00 p.m. — The SkyHopper CubeSat: Big Science with a Tiny Telescope
Michele TRENTI, Faculty, University of Melbourne

Orbiting telescopes, large or small, have been so far confined to complex missions run by government agencies. However, thanks to dramatic technological improvements, CubeSats (nano-satellites based on standardised dimensions) represent a new opportunity to carry out cutting-edge observations from space. In this talk, I will introduce and motivate the SkyHopper mission concept, a proposed 12U CubeSat for Astrophysics and Planetary Science envisioned to be launched by 2022. The spacecraft will be capable of autonomously pointing to new targets in less than 2 minutes, and it will be equipped with the SpaceEye infrared telescope, imaging a 1.4 sqdeg field of view simultaneously at six different wavelengths from 0.8 to 1.7 micron. The combination of timeliness on target and low-noise infrared image quality from space will offer a facility unique in the world to seed Australia's research infrastructure for space astronomy: (1) discovering potentially habitable Earth-size exoplanets transiting in front of nearby cool stars; (2) measuring for the first time the unresolved infrared background light originating from the first generations of stars and galaxies to the 1% precision needed to derive constraints on the epoch of reionization; (3) identifying dying massive stars collapsing into black holes at the edge of the observable Universe, and using them as beacons to study the first galaxies; (4) probing the electromagnetic counterparts of gravitational waves; (5) characterizing interplanetary dust and asteroids to shed light on the formation of our Solar System.

Slides (PDF file) (20.0 MB).

12:00 –12:15 p.m. — The UWL on Parkes -- Early results and future science
Jane KACZMAREK, Postdoctoral Fellow, CSRIO Astronomy & Space Science

Continuing the trend in astronomy to observe over larger and larger bandwidths, the team at CSIRO Astronomy & Space Science has designed, manufactured and recently installed the new Ultra-Wideband Low-frequency (UWL) receiver, which allows for the CSIRO Parkes Radio Telescope to simultaneously observe from 700 MHz – 4 GHz. With its outstanding sensitivity and polarimetric performance, as well as its ability to carry out high-time resolution astronomy, it is anticipated that the UWL will enhance the outcomes of a wide range of scientific projects. Key science projects include sensitive tests of general relativity and the search for gravitational waves, the study of the interiors of neutron stars and mapping the structure of the Galactic magnetic field. In this talk, I will present results from the recent installation and commissioning efforts and discuss some of the future performance goals of the new receiver.

Thu, 28 Jun, 12:15 p.m. to 12:30 p.m. Day ↑ | Top ↑

Poster Sparklers

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

11:00 - 12:30 Session Recording

Thu, 28 Jun, 12:30 p.m. to 2:00 p.m. Day ↑ | Top ↑


Location: ATC 101 foyer

EPOC Chapter Town Hall Meeting

Location: ATC 101

Thu, 28 Jun, 2:00 p.m. to 3:30 p.m. Day ↑ | Top ↑

Special session: GALAH, Gaia and the Galaxy 1

Location: EN 101 — Chair: Simon CAMPBELL, Monash University

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — The GALAH Survey: Data Release 2 and Latest Science Results
Daniel ZUCKER, Faculty, Macquarie University / Australian Astronomical Observatory

The GALAH Survey: Data Release 2 and Latest Science Results The GALAH (GALactic Archaeology with HERMES) survey is an ambitious project to obtain detailed abundances and parameters for a million stars via high-resolution spectroscopy, with the goal of deciphering how the Milky Way formed and has evolved to the present day. GALAH Data Release 2 (DR2), which includes information on over 350,000 stars, represents the first major publication of abundances and parameters from the survey and the largest and most detailed data release from a Galactic archaeology survey to date. Timed to coincide with the extremely complementary second data release from ESA’s Gaia astrometric mission, GALAH DR2 promises to have a major impact on our understanding of the Galaxy’s chemodynamical evolution. I will give an overview of GALAH DR2 and how to access it, and present several exciting new science results based on the dataset.

2:15 –2:30 p.m. — Galactic Arcahaeology with GALAH and K2.
Sanjib SHARMA, Postdoctoral Fellow, The University of Sydney

Asterosesismology in recent years has transformed the field of Galactic archaeology with precise estimates of  mass of red giants. When combined with spectroscopic stellar parameters this yields precise ages. The NASA K2 mission is now providing asteroseismic information about a large sample red giants. The K2HERMES survey is conducting one of the largest spectroscopic followup of targets from the NASA K2 mission. Here I present results from this survey that make use of the GALAH pipeline. I show how this unique dataset is enabling is to put constrains on the properties of the thick disc. Additionally, I show how abundance of various elements vary with time and space in the Galaxy.


2:30 –2:45 p.m. — Galactic Archaeology with HERMES: open clusters and stellar streams
Gayandhi DE SILVA, Research Fellow, AAO/USyd

Open clusters are simple stellar populations that have a critical role in the study of star formation processes, stellar evolution and nucleosynthesis, stellar dynamics, as well as large scale Galactic structure and evolution. The HERMES open cluster program is collecting uniform high resolution, high signal to noise data of open clusters spanning a large range in age, metallicity, and distance. In this presentation, I will give an overview of the developments in Galactic Archaeology based on cluster science, and the first results of the HERMES OC survey.

2:45 –3:00 p.m. — The GALAH Survey: Velocity fluctuations in the Milky Way using red clump giants
Shourya KHANNA, PhD student, SIFA, University of Sydney

If the Galaxy is axisymmetric and in dynamical equilibrium, we expect negligible fluctuations in the residual line-of-sight velocity field. However, non-axisymmetric structures like a bar, spiral arms and merger events can generate velocity fluctuations. Recent results using the APOGEE survey find significant fluctuations in velocity for stars in the midplane (|z|<0.25 kpc) out to 5 kpc, which suggests that the dynamical influence of the Milky Way's bar extends out to the Solar neighborhood. Their measured power spectrum has a characteristic amplitude of 11 km/s on a scale of ~2.5 kpc. The existence of large streaming motions on these scales has important implications for determining the Sun's motion about the Galactic Centre. Using red clump stars from the GALAH (Galactic Archaeology with HERMES) and APOGEE surveys, we map the line-of-sight velocity field around the Sun out to distances of 5 kpc and up to 1.25 kpc from the Galactic Plane. By subtracting a smooth axisymmetric model for the velocity field, we study the residual velocity fluctuations and compare our findings with mock survey generated by GALAXIA based on an axisymmetric, steady state model. We find negligible large-scale fluctuations away from the plane. In the mid-plane, we reproduce the earlier APOGEE power spectrum results but with 20% smaller amplitude (9.1 km/s) after taking into account systematic effects (e.g. volume completeness). The amplitude power is further reduced to 6.9 km/s if a flexible axisymmetric model is used. Additionally, our mock simulations show that, in the plane, the distances are underestimated for high mass red clump stars and this can lead to spurious power with amplitude of about 4.7 km/s. Taking this into account, we estimate the amplitude of real fluctuations to be less than 5.1 km/s, about a factor of two less than the result from APOGEE.

3:00 –3:15 p.m. — Chronostar: Software for the identification of star formation events through the application of machine learning to Gaia DR2
Timothy CRUNDALL, Masters student, ANU

Gaia DR2 contains six-parameter astrometric solutions for 7.2 million stars which we can use to inform the star formation history of our neighbourhood - specifically young, unbounded associations that still retain similar space velocities (moving groups). The discovery of moving groups and their members provide a range of useful science. For example they can provide ages for difficult stars (such as low mass stars) and, in the case of TWA, generate candidates for follow up observations of protoplanetary disks. In fact accurate ages purely from kinematics will be supremely powerful for the analysis of protoplanetary disks. My Masters was spent developing the Chronostar software that can identify the origin point (in space and time) of stars formed from the same event. It applies a Bayesian analysis on kinematic data by modelling the initial configuration of the stars, tracing this forward in time, and comparing with observed kinematic properties. On synthetic data sets it can accurately ages of very young associations (~5 Myr) with 0.2 Myr uncertainty and young associations (~15 Myr) with 0.5 Myr uncertainty. I will present on the application and testing of this technique on synthetic data as well as preliminary results of the application on known moving groups.

3:15 –3:30 p.m. — A Survey of Chromospheric Activity in GALAH Stars
Mark BEAVIS, PhD student, University of Southern Queensland

Initial results and analyses of chromospheric activity in a large sample of GALAH stars is presented. Using activity indicators based on the Hydrogen alpha line, activity levels are measured and analysed with respect to various stellar parameters. This provides an initial characterisation of GALAH stars in terms of chromospheric activity and identifies opportunities for further exploration and analysis. The work also establishes the largest catalogue of stellar activity (number of stars measured) to date.

Slides (PDF file) (2.7 MB).

Special session: Multi-messenger astronomy 1

Location: ATC 101 — Chair: Jade POWELL, Swinburne University of Technology

14:00 - 15:30 Session Recording

2:00 –2:15 p.m. — GOTO in the Advanced Gravitational-Wave Detector Era
Kendall ACKLEY, Postdoctoral Fellow, Monash University

The Gravitational-Wave Optical Transient Observer (GOTO) has begun operations to study electromagnetic counterparts to gravitational-wave events from Advanced LIGO and Virgo. I will discuss the current status of the instrument as we prepare for the next Advanced LIGO and Virgo observing run, the operational challenges that occur when wide-field imaging over the expectedly large probability skymap areas, how we manage the nightly large-scale data sets, and the post-processing techniques we use to identify and filter the myriad of unaffiliated astrophysical transients that are expected to occur in the same field of view.

2:15 –2:30 p.m. — Multimessenger follow-up of continuous gravitational wave candidates
Gregory ASTON, Postdoctoral Fellow, Monash Centre for Astrophysics

Gravitational-wave astronomy is providing new and unique insights into our universe. One, so far, undetected source are long-lived monochromatic signals from rotating neutron stars, either from non-axisymmetries or oscillation modes. Many searches for such signals have already been performed using LIGO/Virgo data. In this talk, we discuss electromagnetic observations used to follow-up candidates found by all-sky searches. Looking for pulsed emission, supernova remnants or quiescent emission from the putative neutron star, we discuss how detections and non-detections across these bands can be combined with population synthesis models to further understand whether the candidates are astrophysical and if so, their history.

2:30 –2:45 p.m. — A turnover in the radio lightcurve of GW170817
Dougal DOBIE, PhD student, University of Sydney

The detection of gravitational waves from the first neutron star merger, GW170817, and the subsequent observations across the entire electromagnetic spectrum has heralded a new era in multi-messenger astronomy. We have been regularly observing the afterglow of GW170817 with the Australia Telescope Compact Array (ATCA), as part of a coordinated monitoring effort with teams from the Very Large Array (VLA) and Giant Metrewave Radio Telescope. In this talk I will discuss the results of our monitoring so far, what can be inferred from the radio lightcurve and prospects for detection of events in the next observing run which will begin later this year. Our observations demonstrate that the radio afterglow peaked at 149+/-2 days post-merger and is now declining in flux density. We see no evidence for evolution in the radio-only spectral index, which remains consistent with optically-thin synchrotron emission connecting the radio, optical, and X-ray regimes. The peak implies a total energy in the synchrotron-emitting component of ~10^50 erg. The temporal decay rate is most consistent with mildly- or non-relativistic material and we do not see evidence for a very energetic off-axis jet, but we cannot distinguish between a lower-energy jet and more isotropic emission.

Slides (PDF file) (1.4 MB).

2:45 –3:00 p.m. — Searches for pulsations in LMXBs
Shanika GALAUDAGE, Undergraduate/honours student, Monash University

Low mass X-ray binary (LMXBs) systems, composed of a neutron star and a low mass companion star, are hypothesised to be a source of continuous gravitational waves that can be detected by interferometric gravitational wave (GW) detectors. The companion stars of these systems have a long lifetime, and the continuous accretion of matter is thought to give rise to asymmetry of the neutron star resulting in continuous gravitational waves. The torque balance model states that a higher accretion rate produces larger-amplitude gravitational waves, hence LMXBs with high X-ray flux are ideal candidates for GW searches. For this project we use archival X-ray data from Sco X-1, Cir X-1 and Cyg X-2 observed by the Rossi X-ray Timing Explorer (RXTE) and run the data through an existing pipeline to search for pulsations. We apply barycentric corrections to the X-ray data and then correct for the variations in efficiency due to the pointing offset of the telescope, the number of proportional counter units in operation for data collection and the deadtime of the instrument. We perform a semi-coherent search for pulsations to obtain constraints on the pulse fraction amplitude for these X-ray sources. The detection of pulsations will immediately reveal the spin frequency of these neutron stars. This constraint can be applied to reduce the volume of the parameter space used for continuous gravitational wave searches and hence improve the sensitivity of these searches.

Slides (PDF file) (1.4 MB).

3:00 –3:15 p.m. — Unveiling the violent Universe with gravitational wave astronomy
Eric HOWELL, Postdoctoral Fellow, University Western Australia

The first gravitational wave (GW) observation of a system of coalescing neutron stars GW170817 and its localisation led to an historic first association of a GW source with a short duration gamma-ray burst GRB170817. The subsequent electromagnetic follow-up campaign was ground-breaking and other than firmly establishing the short gamma-ray burst – binary neutron star association, provided evidence that the low luminosity of GRB170817 (orders of magnitude below the average) was the result of a prompt emission observed at a wide viewing angle. This talk discusses the possible scenarios that could have produced this dim burst and then looks ahead to the next LIGO/Virgo observational run and beyond. It presents coincident GW-gamma-ray burst rate estimates based on the multi-messenger observations of GW170817 and discusses how multi-messenger astronomy can be used to provide further important insights over the remaining years of the advanced GW detector era.

Slides (PDF file) (4.3 MB).

3:15 –3:30 p.m. — LIGO search for gravitational wave counterparts to FRBs
David COWARD, Faculty, University of Western Australia

Advanced LIGO has been searching for gravitational wave (GW) signals in the second science run. The most promising signals to date have been binary black hole mergers. Virgo has recently joined the search, leading to an extraordinary discovery: the first electromagnetic counterpart to a neutron star merger detected in GWs. In the near future other compact binary mergers: black-hole neutron stars should also be detected by the LIGO/Virgo network. Neutron star mergers are now known to be associated with short gamma ray bursts, and may also be the source of Fast Radio Bursts (FRBs). Several classes of FRBs have been identified, repeating bursts and single cataclysmic transients. Both classes of FRBs could be related to gravitational wave sources. We provide an overview of the process of coincident FRBs and gravitational wave searches. We also present the lowest latency search for an optical counterpart to an FRB.

Thu, 28 Jun, 3:30 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

Location: ATC 101 foyer

Thu, 28 Jun, 4:00 p.m. to 5:30 p.m. Day ↑ | Top ↑

General session: Cosmology

Location: ATC 101 — Chair: Janie HOORMANN, University of Queensland

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — Cosmology with the Dark Energy Survey
Tamara DAVIS, Faculty, University of Queensland

The Dark Energy Survey, and its Australian arm "OzDES", are in the final year of a 6-year observing campaign with aim of measuring dark energy through diverse phenomena including weak lensing, baryon acoustic oscillations, cluster cosmology, and type Ia supernovae. Covering 5000 square degrees of the southern sky we expect our final catalogue to include 300 million galaxies and over 3000 supernovae. In addition we are monitoring 771 Active Galactic Nuclei out to redshift z~4 to measure the evolution of supermassive black hole mass over the last 12 billion years. I will give an update of the most exciting results so far, outline the ongoing analyses, and summarise the wealth of data already available for use by the whole community.

Slides (PDF file) (14.6 MB).

4:15 –4:30 p.m. — eROSITA: Cosmology and astrophysics with the next generation X-ray all-sky survey
Kirpal NANDRA, Faculty, Max Planck Institute for Extraterrestrial Physics

eROSITA is the core instrument on the Russian- German Spektrum-Roentgen-Gamma (SRG) mission, scheduled for launch in 2019. It will perform an X-ray all-sky survey about 30 times more sensitive than ROSAT in the soft energy band (0.5- 2 keV), while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the full sky. The design driving science is the detection of large samples of galaxy clusters to redshifts z~1, in order to test cosmological models including Dark Energy. In addition, eROSITA is expected to yield a sample of around 3 million active galactic nuclei, which should revolutionize our view of the evolution of supermassive black holes and their impact on the process of structure and galaxy formation. The survey will also provide new insights into a wide range of other astrophysical phenomena, including isolated Neutron Stars and Black Holes, X-ray binaries, active stars and diffuse emission from the hot plasma within the Galaxy, as well as more exotic ones such as gamma-ray bursts, tidal disruption of stars in galactic nuclei and binary black holes. In this talk I will review the current mission status, and discuss the major scientific goals of the project.

4:30 –4:45 p.m. — Cross-correlation of Cosmic Microwave Background lengsing from POLARBEAR experiment with the H-ATLAS of dusty interstellar medium galaxies
Anh PHAM, PhD student, The University of Melbourne

The POLARBEAR experiment (Ade et al.2014) is a currently on-going promising multiple-stage cosmic microwave background (CMB) probe, with its first phase POLARBEAR-1 data collection commenced in 2012. The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS; Eales et al. 2010) probes the evolution of the dusty interstellar medium in galaxies in the past 5 billion years. Gravitation lensing of the CMB due to large scale structures like galaxies is a prominent barrier to detection of cues from primordial gravitational waves in the CMB. It is thus important to study the correlation between CMB lensing field and the galaxy distribution. This is done with the CMB lensing observed by POLARBEAR and the galaxy catalog from H-ATLAS survey.

Slides (PDF file) (5.5 MB).

4:45 –5:00 p.m. — Polarisation Properties of Extragalactic Radio Sources Observed with SPTpol 500 deg^2 survey
Nikhel GUPTA, Postdoctoral Fellow, School of Physics, University of Melbourne

The polarisation of the Cosmic Microwave Background (CMB) has a wealth of potential information that can be exploited to probe the early Universe. The linear polarisation of the CMB can be decomposed into E-mode and B-mode components. The E-modes are mainly sourced by scalar perturbations and the B-modes by the tensor perturbations and the distortion of E-modes through gravitational lensing by the intervening matter. The B-modes induced by gravitational lensing are potential contaminants towards the detection of primordial B-modes generated by tensor perturbations or inflationary gravitational waves (IGW). The lensing induced B-mode signal is interesting on its own as it can be used to reconstruct the projected gravitational potential between the observer and the last scattering surface. A large contribution to this lensing signal comes from the polarised emissions from extragalactic radio sources and galactic dust. Currently, the polarisation properties of extragalactic radio sources are poorly constrained. In this talk, I will present our ongoing effort to measure the polarisation fraction for the extragalactic radio sources detected in 500 square degree of the southern sky observed with SPTpol, a dual-frequency polarisation-sensitive camera that was deployed on the 10-meter South Pole Telescope.

5:00 –5:15 p.m. — First ever cluster lensing detection in CMB polarisation data
Sanjaykumar PATIL, PhD student, University of Melbourne

Being the largest virialized objects in the Universe, galaxy clusters, provide crucial insight into the standard model of cosmology. Their distribution as a function mass and redshift is extremely sensitive to amplitude of matter fluctuations and dark energy equation of state. Though they are powerful probes of cosmology, they are currently limited by mass uncertainty which is approximately equal to 15%. With future surveys such as LSST and eROSITA providing us with few hundred times larger cluster samples; our ability to fully realise the potential of these samples depends on better mass estimates. Gravitational lensing is widely considered the gold standard in mass estimation. In this talk, I will present the first ever cluster lensing detection in CMB polarisation using data from SPTpol survey and DES cluster catalogue. In polarisation data systematic uncertainties and foreground contributions are minimal making polarisation estimator an optimal one for future surveys. With polarisation data we expect to improve mass uncertainty to ~6.5% for upcoming CMB experiments and to sub-percent level for fourth generation CMB experiments.

5:15 –5:30 p.m. — Updating Microlensing Constraints on Primordial Black Holes
Josh CALCINO, PhD student, University of Queensland

Abstract: The current lack of detection of a dark matter particle has prompted the re-evaluation of alternative dark matter candidates. Primordial Black Holes (PBH) are one such candidate, receiving much attention since the dawn of gravitational wave astronomy. One principle way of constraining PBH dark matter is through gravitational microlensing. Previous microlensing surveys have failed to detect such objects, and therefore place tight constraints on their abundance at certain masses. However, these constraints contain some assumptions that should be reexamined with current knowledge. In particular, the dark halo model that is used to derive constraints is no longer consistent with current observations. I also relax the assumption of a delta function mass distribution, and explore broad PBH mass distributions. My talk with cover these topics, and how they impact the current microlensing constraints. This research is in the process of being published, and is available on arXiv:1803:09205.3.092.

Special session: GALAH, Gaia and the Galaxy 2

Location: EN 101 — Chair: Gayandhi DE SILVA, AAO/USyd

16:00 - 17:30 Session Recording

4:00 –4:15 p.m. — Substructures and tidal distortions in the Magellanic stellar periphery
Dougal MACKEY, Research Fellow, Australian National University

We use a new panoramic imaging survey, conducted with the Dark Energy Camera, to map the stellar periphery of the Large and Small Magellanic Clouds to extremely low surface brightness. Our results starkly illustrate the closely interacting nature of the LMC-SMC pair. We show that the outer LMC disk is strongly distorted, exhibiting an irregular shape, evidence for warping, and significant truncation on the side facing the SMC. Large diffuse stellar substructures are present both to the north and south of the LMC, and in the inter-Cloud region. The SMC is highly disturbed -- we confirm the presence of tidal tails, as well as a large line-of-sight depth on the side closest to the LMC. Young, intermediate-age, and ancient stellar populations in the SMC exhibit strikingly different spatial distributions. Stars with ages < 100 Myr follow the outer ``wing'' feature and extend into a narrow chain of clusters closely tracing the peak of the HI in the Magellanic Bridge. In contrast, those with ages 1.5-4 Gyr exhibit a spheroidal distribution with a centroid offset from that of the oldest stars by several degrees towards the LMC. We speculate that the gravitational influence of the LMC may already have been perturbing the gaseous component of the SMC several Gyr ago. With careful modeling, the variety of substructures and tidal distortions evident in the Magellanic outskirts should tightly constrain the interaction history of the Clouds.

4:15 –4:30 p.m. — Confirmation for a binary origin for blue straggler stars in Magellanic Cloud clusters
Chengyuan LI, Postdoctoral Fellow, Dept of Physics & Astronomy, Macquarie University

Using the Hubble Space Telescope observations, we analyzed populations of blue straggler stars (BSSs) in 25 Magellanic Cloud star clusters. We uncovered a sub-linear correlation between the number of BSSs in the cluster cores and the clusters’ core masses. The numbers of BSSs predicted by single–single stellar collision models do not match the observed BSS populations, even if higher-order collisions are included. This indicates most likely that direct collisions do not represent the primary BSS formation mechanism. Further tests, including analysis of the BSS specific frequencies and their population numbers at larger cluster radii, suggest that binary interactions may be their main formation channel, hinting at an anti-correlation between a cluster’s binary fraction and its core mass.

Slides (PDF file) (7.1 MB).

4:30 –4:45 p.m. — Pushing the envelope on globular clusters
Jeffrey SIMPSON, Postdoctoral Fellow, Australian Astronomical Observatory

We have been undertaking a spectroscopic observing campaign with the Anglo-Australian Telescope of previously unexplored Milky Way stellar clusters. Research into star clusters, and globulars, in particular, has experienced a resurgence in the last decade with the revelation that almost every one of these ancient clusters shows multiple populations with different chemical compositions. None of the proposed formation models has been able to adequately explain this phenomenon. I will present results for three clusters that push the envelope of the parameter space of clusters: the most metal-poor (ESO280-SC06), the lowest mass with multiple populations (ESO452-SC12), and a massive intermediate-age cluster that was hidden by the glare of Sirius (Gaia 1).

4:45 –5:00 p.m. — Post-Asymptotic Giant Branch (post-AGB) Stars as Tracers of the Origin of Elements in the Universe
Devika KAMATH, Faculty, Macquarie University

How are the elements in the Universe synthesised? This is one of the defining questions of astrophysics. Low- and intermediate-mass (LIM) stars (0.8 to 8Msun) are key contributors to the chemical enrichment of their host galaxies. They are major producers of elements such as carbon, nitrogen, and about half of the elements heavier than iron. However, understanding how LIM stars produce their elements remains an unsolved problem. Post-AGB stars bear signatures of the entire nucleosynthesis that took place prior to and during the chemically-rich Asymptotic Giant Branch (AGB) phase of a LIM star’s life and are therefore ideal tracers of element production. Our studies have revealed that element production in low-mass stars remains shrouded in mystery as the objects display a much larger chemical diversity than anticipated. While some are the most carbon and s-process rich objects known to date, others are not enriched at all. Additionally, significant discrepancies exist between the observed and predicted abundances of post-AGB stars; reflecting on our poor understanding of the crucial AGB nucleosynthesis: the treatment of convective mixing in both the envelope and the deeper interior, as well as the s-process nucleosynthesis. In this talk I will present our efforts and the results from our comprehensive high-resolution spectroscopic studies on post-AGB stars using facilities such as ESO, and surveys such as GALAH, and APOGEE, to eliminate uncertainties that govern the crucial AGB nucleosynthesis and demystify the element production in LIM stars.

Slides (PDF file) (4.1 MB).

5:00 –5:15 p.m. — On the Peculiar Lives of Low-Mass Primordial Stars
Simon CAMPBELL, Research Fellow, Monash University

Models of zero metallicity and extremely metal-poor stars show that they evolve differently to their more metal-rich counterparts. In particular they suffer violent episodes that very often lead to extreme carbon enrichment at the surface. The large amounts of carbon in their atmospheres has a fundamental effect on their further evolution. The carbon enrichment may also be accompanied by s- or i-process products produced during the violent episodes, thus making the stars intrinsic CEMP or CEMP-s/i stars. In this talk I will describe the evolution of a primordial star from the main sequence through to the thermally-pulsing asymptotic branch phase (AGB), and present a summary of the evolutionary outcomes we have found in our grid of zero metallicity and extremely metal-poor models. We have also calculated the AGB nucleosynthetic yields for these stars, with the caveat that they suffer from many uncertainties. Finally I will briefly touch on our initial attempts at using 3D hydrodynamics to model the violent episodes.

Slides (PDF file) (2.3 MB).

5:15 –5:30 p.m. — Dredge-up Main-Sequence O stars: implications for the Epoch of Reionization and chemical evolution of the Universe
Arpita ROY, Postdoctoral Fellow, ANU

Classical Wolf-Rayet (WR) stars start their lives as Main-Sequence (MS) O-stars and they lose most of their outer hydrogen layers via massive wind-loss and expose their cores allowing the nucleosynthesis products to become visible at the stellar surfaces. These stars can also have high surface abundances of Helium and Nitrogen at the MS via rotational dredge-up and therefore need not necessarily have to lose all their hydrogen layers. Our Galactic centre hosts Arches cluster which contains such stars in large numbers. We study the evolution of these massive stars ($60 \leqslant$ M/M$_{\odot} \leqslant 120$) for various values of v/v$_{\rm crit}$; the rotation speed as a fraction of the critical velocity, for a range of metallicities ([Fe/H]$=0.0, -1.0, -2.0$) and alpha-enhancements ([$\alpha$/Fe]$=0.0, 0.2, 0.4$) using MIST (MESA Isochrone Stellar Tracks) 1-dimensional stellar code. We show that at all metallicities, the rotational dredge-up allows the CNO-cycle products (He, N) to reach the stellar surface even without much wind loss. We also show that at high metallicities, even without any rotation, the thermohaline mixing allows the substantial dredge-up of the nucleosynthesis products to the surface. Due to the dredge-up of heavy elements, the surface opacities in these stars change and therefore the effective temperature changes which eventually affects the production of ionizing photons at high red-shifts. These stars also have implications for the evolution of the N/O ratio in the interstellar medium (ISM) of galaxies at high red-shift.

Thu, 28 Jun, 7:00 p.m. to 11:00 p.m. Day ↑ | Top ↑

ASA Conference Dinner

Registration required

7:00 p.m. – 11:00 p.m.

The ASA conference dinner will be held on Thursday, the 28th of June, at the Coral Atoll room of SEA LIFE Melbourne Aquarium

The information that Glenn presented can be viewed here:

The cost of the dinner is ...

More info →

Fri, 29 Jun

8:30–9:00 a.m. | 9:00–10:30 a.m. | 10:30–11:00 a.m. | 11:00a.m.–12:30 p.m. | 12:30–1:15 p.m. | 1:15–1:45 p.m. | 1:45–2:30 p.m. | 2:30–2:45 p.m.

Fri, 29 Jun, 8:30 a.m. to 9:00 a.m. Day ↑ | Top ↑

Arrival tea/coffee

Location: ATC 101 foyer

Fri, 29 Jun, 9:00 a.m. to 10:30 a.m. Day ↑ | Top ↑

General session: Extragalactic astronomy 3

Location: EN 101 — Chair: Tamara DAVIS, University of Queensland

09:00 - 10:30 Session Recording

9:00 –9:15 a.m. — Asymmetric radio galaxies as probes of jet-environment interaction
Stas SHABALA, Faculty, University of Tasmania

Feedback from radio jets associated with supermassive black holes is widely acknowledged to be a key driver of galaxy evolution in the most massive galaxies and galaxy clusters. Over the next decade, radio continuum surveys will probe radio Active Galactic Nucleus (AGN) populations across a wide range of environments and cosmic epochs. However, quantifying the energetics of AGN jets - and, hence, their contribution to feedback - is challenging. A major confounding variable is the environment into which the jets expand. X-ray observations are the “gold standard” for quantifying jet environments on 10-100s kpc scales, however these are limited to gas-rich systems and low redshifts. An alternative approach, pioneered by our group, is to use galaxy clustering as a proxy for the gas distribution. Asymmetric radio sources provide the ideal laboratory for probing the jet-environment interaction: the two bipolar jets are intrinsically identical, but are expected to produce radio lobes with differing properties if the gaseous environment into which the jets are expanding is asymmetric. We present a sample of asymmetric radio galaxies from the Citizen Science project Radio Galaxy Zoo. We find that radio source asymmetry is correlated with asymmetry in galaxy clustering, and the correlations are quantitatively consistent with expectations from analytical radio source models. Using the PLUTO code, we perform the first numerical simulations of jets in asymmetric environments, and confirm conclusions from our analytical modeling work. Moreover, our simulations suggest that much of the scatter in the observed radio source - galaxy clustering asymmetry relations can be naturally explained by radio AGN hosts being found in a variety of environments. We conclude that galaxy clustering is a useful measure of radio source environment. Application of radio source models to surveys such as the ATCA legacy GLASS project holds great promise in unravelling the complex connections between radio sources and their environments.

9:15 –9:30 a.m. — Probing the connection between radio galaxy morphology and environment with GLASS
Jonathan ROGERS, PhD student, University of Tasmania

Accretion of gas onto super massive black holes results in the production of relativistic plasma jets. The interaction between these jets and the surrounding environment on galaxy and group/cluster scales has profound effects on the host galaxy evolution and strongly influences the resulting AGN structure. Observations of extragalactic radio sources show a morphological dichotomy, with sources appearing core brightened (Faranoff-Riley Type I, FR- I) or edge brightened (FR-II). This dichotomy has been linked to intrinsic jet properties, and is also strongly dependent on the surrounding environment. We present the current status and data products of the GAMA Legacy ATCA Southern Survey (GLASS). We then use GLASS observations to construct a catalogue of FR-I and FR-II radio sources, complete with environment information via host galaxy photometry, spectroscopy, and cluster information. GLASS is a deep (∼24μJy rms at 5.5GHz, ∼40μJy rms at 9.5GHz), wide (60sq degree) survey of GAMAs southern G23 field at 5.5 and 9.5GHz, complemented by GAMA photometric and spectroscopic surveys of the same region. The sub 2′′ resolution of ATCA at these frequencies probes the detailed AGN structure not apparent in lower frequency surveys. We present the results of an investigation into the radio AGN morphology-environment connection.

9:30 –9:45 a.m. — Catching Sub-kpc Scale AGN Feedback in the Act in the Compact Steep Spectrum source 4C 31.04
Henry ZOVARO, PhD student, The Australian National University

The peaked radio spectrum and compact radio emission of Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) sources indicates that they harbour young jets temporarily confined by a dense interstellar medium. Observing these sources therefore enables us to study Active Galactic Nucleus (AGN) feedback processes within the host galaxy in the early stages of radio activity. In my talk I will report on the discovery of sub-kpc scale jet-ISM interaction, in the form of a jet-driven bubble, in the host galaxy of the $z = 0.0602$ CSS source 4C~31.04. 4C~31.04 has a compact ($\sim 100$~pc) double-lobed radio morphology, and is believed to be a very young ($\sim 10^3$~yr old) AGN. Its host galaxy, the giant elliptical MCG~5-4-18, has a dense, multi-phase circumnuclear disc that has been detected in H~\textsci{i}, CO and HCO$^+$ with an estimated gas mass of $M_\text{gas} \sim 10^{10}~M_\odot$. Using high spatial resolution AO-assisted $H$- and $K$-band integral field Gemini/NIFS observations, we probe two new phases of the circumnuclear medium: (1) the warm ($\sim 1000$~K) molecular gas, traced by ro-vibrational transitions of H$_2$ in the near-infrared, and (2), Fe~\textsc{ii}, traced by the [Fe~\textsc{ii}]1.644$\mu$m line, at a much higher angular resolution than previous studies. We detect the warm H$_2$ in the form of a inflated kpc-scale torus, whilst the [Fe~\textsc{ii}] emission is localised to the innermost $\approx 300$~pc of the galaxy. We conclude that the [Fe~\textsc{ii}] emission, excited by fast J-shocks, traces a bubble of outflowing gas driven by the jet-driven forward shock. We find the warm H$_2$ torus is also shock-excited, although its distance from the nucleus is too great to be caused by jet activity. We instead conclude that the shocks are a result of accretion processes.

9:45 –10:00 a.m. — AGN Reverberation Mapping with OzDES
Janie HOORMANN, Postdoctoral Fellow, University of Queensland

AGN reverberation mapping measures the time delays in the emission from the inner regions of active galaxies surrounding the central supermassive black hole. Measuring this time delay provides a way to constrain the geometry of these regions which are too small to image directly which can then be used to measure the mass of the black hole. The Australian Dark Energy Survey (OzDES) is regularly observing 771 AGN with redshifts out to z~4 as part of its reverberation mapping program. It is expected that OzDES will be able to recover masses for 40% of its AGN. This is not only a significant increase over the current state-of-the-art sample which includes around 110 measurements but also a much wider redshift range than previously measured. With this data we plan to measure how supermassive black holes have evolved over the past 12 billion years and test the theory that AGN can be used as standard candles in cosmology. OzDES is about to begin its sixth and final year of observations. We will present the current status of the reverberation mapping campaign including our first lag measurements using the CIV emission line observed in high redshift galaxies.

Slides (PDF file) (900.9 KB).

10:00 –10:15 a.m. — Exploring High-z Black Hole - Bulge Relations With Semi-Analytics
Madeline MARSHALL, PhD student, University of Melbourne

Observed correlations between the masses of supermassive black holes and the properties of their host galaxies, such as their mass and velocity dispersion, indicate that there is a co-evolution of galaxies and their black holes. Studying these relations at higher redshifts will help to understand the physical mechanisms that cause this coeval growth history. Using a new update to the Meraxes semi-analytic model, I examine the evolution of black holes and the properties of their host galaxies at high redshift. I find that the black hole - bulge mass relation shows only slight evolution, which supports the conclusions of recent observations. We will test these results with forthcoming observations using guaranteed time on JWST.

Slides (PDF file) (4.8 MB).

10:15 –10:30 a.m. — The next-generation automated radio source classifier based upon Radio Galaxy Zoo and advanced machine learning algorithms
O. Ivy WONG, Research Fellow, ICRAR/UWA

The upcoming Evolutionary Map of the Universe (EMU) all-sky radio continuum survey using the Australian Square Kilometre Array Pathfinder (ASKAP) expects to detect millions of radio sources. Morphological classifications of radio galaxies have traditionally been done by eye but these are practical only for samples of up to a few thousand radio sources. Radio Galaxy Zoo is an online citizen science project that enlists the help of the public to cross-match radio sources, often with complex structure, to host galaxies in infrared images. While crowdsourcing through citizen science provides a significant improvement in source classification efficiency, this improvement is still insufficient to handle the classification of millions of sources from surveys such as EMU. Hence, further development of automated classification methods is necessary to maximise the scientific return of surveys such as EMU. In this talk, I will describe the Radio Galaxy Zoo's collaboration with several international machine learning teams to develop the next-generation automated classifiers. I will specifically focus on a GPU-based proof-of-concept automated radio source morphology classifier based upon a Region-based Convolutional Neural Network (R-CNN) algorithm that has been trained on the Data Release 1 (DR1) of the Radio Galaxy Zoo citizen science project. The main purpose of this demonstrator classifier is to enable the end user to obtain radio source morphology classifications from a simple input of a radio image and an infrared image of the same region. This is the first publicly-available radio source morphology classifier that is capable of locating and associating discrete and extended components of radio sources in an automated and accurate fashion. In addition to presenting an open-source publicly-available classifier, a CPU-based demonstrator is included in our GitHub repository.

Special session: Multi-messenger astronomy 2

Location: ATC 101 — Chair: Kendall ACKLEY, Monash University

09:00 - 10:30 Session Recording

9:00 –9:15 a.m. — Optimising 3G gravitational wave detectors for neutron star science
Francisco HERNANDEZ, PhD student, Monash University

The first detection of a binary neutron star system using gravitational waves has marked a new way to understand matter at extreme dense conditions. Although first steps towards determining neutron star's equation of state (EoS) using tidal deformabilities have been done, there are still plenty of questions that remain unanswered. With current technology, interferometers are tuned to have maximum sensitivity at $\sim 100 $ Hz, where information of parameters such as the binary mass and spin of neutron stars can be extracted. However, the gravitational wave spectrum that contains information about matter is found at higher frequencies, where current interferometers' sensitivity are limited by shot noise, making the measurement of the neutron star's EoS difficult with available facilities. For this reason, we study our ability to do neutron star science using high-frequency dedicated third generation interferometers.

9:15 –9:30 a.m. — Using machine learning algorithms to enable gravitational-wave detection of short duration binary neutron star remnants
Paul EASTER, PhD student, Monash Univesity

In 2017, gravitational waves from the inspiral phase of a binary neutron star merger were first detected. The opportunity exists to detect signals also from short-lived post-merger remnants as the sensitivity of gravitational-wave detectors increase. Gravitational waveforms are required to extract these weak signals from the noise, however it is computationally very expensive to generate such waveforms. I will present a method based on machine learning to generate millions of gravitational-wave templates of post-merger signals that will enable searches for these remnants. Successful detection of post merger remnants will provide insight into the physics of neutron stars.

Slides (PDF file) (656.2 KB).

9:30 –9:45 a.m. — Investigating black hole spin with gravitational waves
Grant David MEADORS, Research Fellow, Monash University

When two black holes coalesce, the spin is imprinted on the associated gravitational waveform. Black hole spin parallel to the orbital angular momentum changes the merger frequency, and therefore the time the signal spends in the observing band of a gravitational-wave detector. The black hole spin perpendicular to the orbital angular momentum causes precession, which modulates the envelope of the gravitational-wave signal. However, the effect of precession is difficult to measure and has not been identified in the detections of binary black hole mergers. In this talk I will describe how black hole precession can be detected using an ensemble of binary black hole mergers. Furthermore, by comparing different prescriptions for the effect of black hole spin we can perform new tests on the orbital dynamics of general relativity.

Slides (PDF file) (1.5 MB).

9:45 –10:00 a.m. — Dances with Death: The Dynamics of Compact Binary Pairs as Gravitational Wave Sources
Sera Jade RAUHUT, Undergraduate/honours student, Swinburne University of Technology

In this work we analyze simulations of black hole and neutron star binary dynamics in star clusters, exploring their formation, inspiral times, cluster ejections and coalescence. We use an alternative approach to dense cluster N-body statistical mechanics simulating a dense core populated exclusively with black holes and neutron stars. The dynamics within the core of the globular cluster are investigated to determine the likelihood of homogenous and heterogenous binary formations and further statistics describing their systematic evolution. The results will assist observers by developing a framework for future gravitational wave source detection strategies and interpretations.

10:00 –10:15 a.m. — An X-ray guided search for gravitational waves
Nikhil SARIN, PhD student, Monash University

Observations of X-ray afterglows in short gamma-ray bursts indicate the presence of a long-lived binary neutron star post-merger remnant. I will discuss gravitational-wave emission mechanisms for such a post-merger remnant and present a method to search for gravitational waves from this remnant using coincident X-ray afterglow observations to guide the search.

Slides (PDF file) (6.5 MB).

10:15 –10:30 a.m. — Insights into double neutron star and double black hole formation with COMPAS
Simon STEVENSON, Postdoctoral Fellow, Swinburne University of Technology

Gravitational wave observations of a double neutron star merger GW170817 along with 5 double black hole mergers offer a new insight into the formation of these relativistic binaries. Such compact binaries are thought to form as the end point of the evolution of isolated massive stellar binaries. There are several poorly constrained stages of binary evolution such as supernovae and common envelope evolution. We use the gravitational wave observations and our platform COMPAS to constrain these uncertain parameters in isolated binary evolution.

Fri, 29 Jun, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Location: ATC 101 foyer

Fri, 29 Jun, 11:00 a.m. to 12:30 p.m. Day ↑ | Top ↑

General session: Extragalactic astronomy 4

Location: EN 101 — Chair: Nikki NIELSEN, Swinburne University of Technology

11:00 - 12:30 Session Recording

11:00 –11:15 a.m. — Titans of the Early Universe: The origin of the most massive, high-redshift quasars
Tyrone E. WOODS, Research Fellow, Monash University

The discovery of billion solar mass quasars at redshifts of 6–7 challenges our understanding of the early Universe; how did such massive objects form in the first billion years? Observational constraints and numerical simulations increasingly favour the "direct collapse" scenario. In this case, an atomically-cooled halo of primordial composition accretes rapidly onto a single stellar core, ultimately collapsing through the Chandrasekhar-Feynman instability to produce a supermassive (~100,000 solar mass) "seed" black hole. In this talk, I'll present a systematic study of the lives and deaths of these objects, using the 1D implicit hydrodynamics and stellar evolution code KEPLER. We include post-Newtonian corrections to gravity and a detailed treatment of nuclear burning processes using an adaptive network. We find a simple relation between the infall rate and the final mass at collapse, and rule out the existence of rapidly-rotating supermassive stars. I'll also discuss the possibility of early chemical enrichment from these objects, observational prospects in the era of the JWST, and other future directions.

Slides (PDF file) (3.9 MB).

11:15 –11:30 a.m. — Infer Structure of Quasar with Machine Learning
Suk Yee YONG, PhD student, The University of Melbourne

The broad absorption line quasar (BALQ) is a minority class of quasar population that displays deep absorption features. One explanation of the BAL phenomenon is based on orientation model, which often assumes a disk-wind model with a narrow wind opening angle. In this context, the emission properties between the BALQs and non-BALQs are expected to be different as they are seen at different inclinations. Using supervised machine learning, we attempt to classify the two populations by their continuum and emission line characteristics. We find that none of the investigated features are able to differentiate the two samples. This contradicts the thin disk-wind model and we propose a modified model consisting of clumpy wind encompassing a wide range of angles.

Slides (PDF file) (1.7 MB).

11:30 –11:45 a.m. — Calibrating the James Webb Space Telescope filters as star formation rate indicators
Madhooshi Ruwanpura SENARATH, PhD student, Monash centre for Astrophysics, School of physics and Astronomy, Monash University

We have calibrated the 6.5 m James Webb Space Telescope (JWST) mid-infrared filters as star formation rate indicators, using JWST photometry synthesized from \textit{Spitzer} spectra of low redshift galaxies. We use Balmer decrement corrected $\rm{H\alpha}$ luminosity to empirically calibrate the \textit{Spitzer}, WISE and JWST mid-infrared filters as star formation rate indicators. Our \textit{Spitzer} and WISE calibrations utilizing photometry synthesized from spectra are in good agreement with recent calibrations from the literature. For galaxies with a $\rm{H\alpha}$ luminosity of $\rm{10^{40}}~erg~s^{-1}$, we find that the corresponding JWST mid-infrared $\rm{\nu L_{\nu}}$ luminosity is between $\rm{10^{40.49}}$ and $\rm{10^{41.00}}~erg~s^{-1}$. Power-law fits of the data have indices between 1.15 and 1.30. We find that the scatter in the JWST filter calibrations decreases with increasing wavelength from 0.39 to 0.19 dex, although F1000W is an exception where the scatter is just 0.23 dex.

Slides (PDF file) (18.1 MB).

11:45 a.m. –12:00 p.m. — Star-forming properties of galaxies in the core and filamentary regions of the merging galaxy cluster A2744
Tiffany E. DAY, PhD student, Macquarie University

Clusters of galaxies are the largest and most massive virialized objects in the observable Universe, growing hierarchically over cosmic time by the accretion of surrounding gas, dust and matter, including the infall of individual field galaxies or groups of galaxies. More rarely, clusters of galaxies grow by means of a merger between two or more clusters, providing the most extreme example of this hierarchical formation scenario. Whilst the physical mechanisms which drive galaxy transformation in cluster environments are well studied, the effect that the hierarchical growth of a cluster has on these mechanisms is not well understood. Can hierarchical growth enhance and/or modulate these transformation mechanisms? There has been some disagreement as to the importance of the cluster-specific mechanisms at play, and whether it is the cluster environment that is most important in suppressing the star formation or whether this occurs prior to a galaxy entering the viralized region of the cluster, i.e. a form of "pre-processing" in the filamentary regions surrounding the cluster. The simplest way to address this conundrum is to consider a major merger event, whereby any measurable effects will be amplified. The massive cluster Abell 2744 is a prime candidate for such a study, being one of the most complicated merging systems known. Recent studies have traced filamentary structure surrounding A2744 in the hot gas, along with weak lensing observations of the dark matter. Combined with new optical spectroscopic data, this provides a unique case where both filaments and central regions are traced by all three sets of observations. In this talk, I will focus on my work to probe both the outer filamentary structures of A2744 to well beyond the cluster virial radius, as well as the complex merging core of the cluster. This analysis provides a better understanding of how different environments can influence star formation, cluster galaxy transformation and evolution.

Slides (PDF file) (4.6 MB).

12:00 –12:15 p.m. — The globular cluster system of NGC 4526
Leonie CHEVALIER, Masters student, Swinburne University of Technology

With ages up to ~ 12.8 Gyr globular clusters (GC) are one of the oldest objects we observe in galaxies and are thought to preserve their parent galaxy's chemo-dynamical properties at the time of their formation. A single galaxy can have tens of thousands of GCs associated with it. Globular cluster systems have long been thought to be a useful tool in constraining galaxy formation scenarios and even to infer a galaxy's individual formation history. More recently GCs have been used to infer dark matter masses of galaxies. I will be talking about the GC system of the lenticular galaxy NGC 4526. We used Subaru imaging to study the system's full extent and infer the total number of GCs as well as the substructure in the GC system. Additionally we used DEIMOS spectrograph on the Keck telescope to obtain radial velocities for 106 GCs to be used in studying the dark matter content of NGC 4526. The combination of multiband photometric data in combination with the spectroscopic data gained by DEIMOS is a significant improvement on existing data sets that only partially imaged the GC system. To put our findings into a broader context I compared NGC 4526 to the results of 26 other elliptical and lenticular galaxies (and their GC systems) from existing literature. Additionally we investigated the dark matter content of NGC 4526 and how this measurement is dependent on sample selection and model assumptions. What we found included an unusually high fraction of 80% metal poor GCs and dark matter fraction for a galaxy of this mass. In fact it was one of the highest metal poor fractions observed in our sample of 27 galaxies. Interestingly the GC system itself did not appear overly extended. I propose that this particular galaxy most likely formed through a series of minor mergers.

12:15 –12:30 p.m. — The Chemical and Dynamical Composition of NGC 3115
Adriano POCI, PhD student, Macquarie University

The formation history of a galaxy is the integration of all dynamical and chemical processes over its lifetime. Typically, models of galactic dynamics and stellar populations are considered independently from one another, while in reality they are intimately connected facets of galaxy formation. We exploit remarkable new spatially-resolved data from the MUSE integral-field unit to conduct a combined dynamics/stellar-populations analysis of the nearby S0 galaxy NGC3115, in order to infer its true formation history. I will present the detailed models that go into this analysis - namely the fully general, triaxial Schwarzschild orbit-based dynamical models, and full-spectral-fitting star-formation histories, as well as how we combine these two concepts to uncover the assembly history of this galaxy.

Special session: Multi-messenger astronomy 3

Location: ATC 101 — Chair: Eric HOWELL, University Western Australia

11:00 - 12:30 Session Recording

11:00 –11:15 a.m. — Next Generation Gravitational Wave Observatories - The Network
Bram SLAGMOLEN, Research Fellow, The Australian National University

The current gravitational wave detector network consist of the two Advanced LIGO detectors and the Advanced Virgo detector, with KAGRA joining in the near future. The LIGO and Virgo detectors have observed the merger of black holes pairs and binary neutron star pairs. The three detectors allowed the sky location of the neutron star merger to be observed with sufficient precision to enable electro-magnetic observations of the source. This provided a large data set, rich in science and full of discoveries. These second-generation gravitational wave detectors are approaching their design sensitivities, ready to observe and detect future events. The recent discoveries are rapidly changing the astrophysics landscape, and astronomers are eager to follow future triggers of gravitational wave observations. Next generation detectors are being designed to expand our reach into the universe. These detectors will operate as a global network of detectors. The Gravitational Wave International Committee (GWIC) is leading the development of an international science case for future base detectors. The European Einstein-Telescope is a triangular shaped detector with 10 km long sides located hundreds of meters underground, while the US based Cosmic Explorer proposal is a 40 km long detector. Here we will discuss the research and development of technologies under taken by Australian researchers for these third generation gravitational wave detectors.

11:15 –11:30 a.m. — Research topics at the University of Western Australia towards third generation gravitational wave detectors
Joris VAN HEIJNINGEN, Postdoctoral Fellow, University of Western Australia

The gravitational wave (GW) detector network is now comprised of Advanced LIGO and Advanced Virgo and expected to welcome KAGRA and LIGO India within 5 years or so. The first two observation runs in the second generation era (2015 onwards) have been very successful to the newly founded field of gravitational wave astronomy. We observed GWs for the first time, detected in total five binary black hole mergers and as a grand dessert, observed a collision of two neutron stars last August. The subsequent recording of the electromagnetic counterparts, observed by about 60% of the world's astronomer, ushered in a new phenomenon as well: multi-messenger astronomy. Gravitational wave physics and astronomy are expected to produce even more highly impactful results. It is impossible to predict, but exciting to imagine, what astronomical surprises are on their way to Earth...

While current infrastructures are still expected to be able to host competitive science for the coming few decades, plans for a so-called third generation of detectors are off to a good start with Cosmic Explorer and Einstein Telescope in the US and Europe, respectively. However, many technological challenges await us if we want to achieve the sensitivities that will give us access to our science goals, e.g. probing the early Universe at high (z>10) redshift. This talk aims to give an overview of the technological advances achieved and pursued at the University of Western Australia. It will touch on our efforts to 

- increase the bandwidth of GW detectors by using so-called white light cavities; 

- reduce displacement noise at the test mass level by the use of Silicon optics;

- design intefereometers free of (parametric) instabilities;

- and reduce the influence of seismic noise including so-called Newtonian Noise. 

Slides (PDF file) (48.8 MB).

11:30 –11:45 a.m. — Parkes Pulsar Timing Array
Stefan OSLOWSKI, Research Fellow, Swinburne University of Technology

The gravitational wave spectrum spans a large range of frequencies with various experiments covering different parts of the spectrum. At the low end of the spectrum, in the nanoHertz regime, we use so-called Pulsar Timing Arrays (PTAs) to try and detect gravitational waves. PTAs observe tens of millisecond pulsars spread throughout our Galaxy to form a galactic-scale detector. The primary signal PTAs attempt to detect are mergers of supermassive blackholes but we are also sensitive to more exotic sources like cosmic strings. PTAs are also excellent tools for other purposes, such as time keeping or measuring the masses of planets in the Solar System. During this talk I'll provide you with an overview of the history of PTAs, current efforts and struggles, as well as the outlook into the bright future with focus on the results of the Australian experiment, the Parkes Pulsar Timing Array.

Slides (PDF file) (6.3 MB).

11:45 a.m. –12:00 p.m. — Improving gravitational wave science with machine learning
Jade POWELL, Postdoctoral Fellow, Swinburne University of Technology

Machine learning is a very active area of research and development within the LIGO Scientific Collaboration and the Virgo collaboration. In this talk I give an overview of how machine learning techniques can improve gravitational wave science for current and future gravitational wave detectors. This includes improving the sensitivity of searches for binary systems and core-collapse supernovae, rejecting false positives in gravitational wave searches, classification of transient noise artefacts in the detector data, and faster and more accurate measurement of the astrophysical parameters of gravitational wave sources.

12:00 –12:15 p.m. — Hidden Markov model tracking of continuous gravitational waves from binary neutron stars
Patrick CLEARWATER, PhD student, The University of Melbourne

The first detections of gravitational waves by the Laser Interferometer Gravitational Wave Observatory (LIGO) have begun the era of gravitational wave astronomy. While discoveries so far have been transient signals from coalescing binary systems, continuous waves from persistent sources, such as neutron stars in low-mass X-ray binaries (LMXBs), are an important target for future searches. One challenge to be overcome when searching for such targets is spin wandering: intrinsic, unpredictable variation in a neutron star's spin frequency (and consequently the frequency of gravitational radiation), which limits the maximum length of a coherent search at a single frequency to approximately 10 days. An effective solution for this is using a hidden Markov model (HMM) to track the most probable frequency path in a computationally efficient manner. When combined with the J-statistic, a matched filter accounting for the binary orbit of the source, the HMM is a potent and computationally-efficient tool for gravitational wave data analysis, with potential applications in both gravitational waves and astronomy in general.

12:15 –12:30 p.m. — Inferring the population properties of binary black holes.
Colm TALBOT, PhD student, Monash University

Observations by advanced LIGO / Virgo are revealing a previously unexplored population of black holes between 5 and 50 solar masses. By constructing phenomenologically motivated parameterised models for the distribution of compact binaries we can learn how these objects form. In this talk, I will investigate two such models. I will show how gravitational-wave detections can teach us about (1) the fraction of merging binaries which formed dynamically in globular clusters, (2) the magnitude of black hole natal kicks and (3) the remnants of pulsational pair-instability supernovae.

Fri, 29 Jun, 12:30 p.m. to 1:15 p.m. Day ↑ | Top ↑


Location: ATC 101 foyer

Fri, 29 Jun, 1:15 p.m. to 1:45 p.m. Day ↑ | Top ↑

Invited Talk

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

13:15 - 15:30 Session Recording

1:15 –1:45 p.m. — Listening to the Universe: Ground Based Gravitational Wave Astronomy and Australia's Future Role
David BLAIR, Faculty, University of Western Australia

Results from the first two years of gravitational wave astronomy indicate that binary black holes coalesce within the Hubble volume at a rate of one every 4 minutes, while neutron stars coalesce at a rate of ~4 per minute. The origin of the binary black holes is uncertain. They could be remnants of coevolved binaries, they could be dynamically formed, or they could be of primordial origin. Neutron star coalescence has already given a clue to the neutron star equation of state, but sensitivity in the 1-4kHz range is inadequate to properly probe neutron star matter. Equally, the lack of sensitivity at high frequencies prevents black hole quasi-normal modes to be used to obtain black hole angular momentum data which can help distinguish formation mechanisms and provide deeper testing of general relativity near the event horizon.

This talk will report on the modelling of a pair 8km arm length Advanced LIGO type detectors in the Asia/Australia region. Such detectors could be the first stage of a future third generation detectors. Sensitivity improvements could be based on white light signal recycling and other quantum optic techniques. Modelling shows the significant benefits of  expanding the  world array of detectors. Even modest improvements will allow gravitational wave astronomy to monitor black hole coalescence across the Hubble volume, and to deeply probe the neutron star matter. This talk will review the various concepts for improved detectors and show that an improved world array is capable of mapping large scale black hole density fluctuations, which in turn may help determine the total population of black holes in the universe.

Fri, 29 Jun, 1:45 p.m. to 2:30 p.m. Day ↑ | Top ↑

Special session: Exoplanets & galactic structure in the TESS era

Location: ATC 101 — Chair: Darren CROTON, Swinburne University of Technology

13:15 - 15:30 Session Recording

1:45 –2:00 p.m. — The FunnelWeb Survey: Spectroscopic Stellar Parameters for All Southern Stars in the Gaia Era
Adam RAINS, PhD student, Australian National University

The FunnelWeb Survey, known simply as `FunnelWeb', is a multi-object stellar survey of the Southern Hemisphere beginning in mid-2018. The FunnelWeb main survey will cover the entire southern sky, excluding only the most crowded regions, ($\delta \leq 0$ degree, $|b| \geq 10$ degree) and will obtain high-quality (S/N$\sim$100) optical spectra (370-870$\,$nm, R $\geq$ 2000) for some $\sim$\,1.8 million stars down to a magnitude of G=14.5, aiming for 99\% completeness at the G=12.5 level. The survey is enabled by the TAIPAN instrument on the recently-refurbished 1.2\,m UK-Schmidt Telescope at Siding Spring Observatory, Australia, which is able to simultaneously robotically position 150 optical fibres within the 6 degree field of view. In addition to synergy with the Gaia and TESS missions, the main goal of the survey is to produce a spectral library with detailed stellar parameters (including T$_{\rm eff}$, log(g), [Fe/H] and [alpha/Fe]) for all stars observed, and the identification of young stars though Li and kinematics. This talk gives an overview of the survey as a whole, before going into more detail on how FunnelWeb will obtain parameters for each star.

Slides (PDF file) (9.0 MB).

2:00 –2:15 p.m. — The photometric selection of M-dwarfs using Gaia, WISE and 2MASS photometry
John BENTLEY, PhD student, University of New South Wales

I will present criteria for the photometric selection of M-dwarfs using all-sky photometry, with a view to identifying M-dwarf candidates for inclusion in the input catalogues of upcoming all-sky surveys, including TESS and FunnelWeb. The criteria are based on Gaia, WISE and 2MASS all-sky photometry, and deliberately do not rely on astrometric information. Even with the availability of truly distance-limited samples from Gaia DR2, this approach has the significant benefit of delivering a sample unbiased with regard to space velocity. Our criteria were developed by using Galaxia synthetic galaxy model predictions to evaluate both M-dwarf completeness and false-positive detections (i.e. non-M-dwarf contamination rates). We have derived two sets of Gaia G > 14.5 criteria - a ``high-completeness'' set that contains as many M-dwarfs as possible, regardless of the number of non-M-dwarfs selected and a ``low-contamination'' set that prioritises the stars most likely to be M-dwarfs at a cost of a reduction in completeness. Comparison of the high-completeness set with the TESS Input Catalogue has identified 234 stars not currently in that catalogue, which preliminary analysis suggests could be useful M-dwarf targets for TESS. We also compared the criteria to selection via absolute magnitude and a combination of both methods. We found that colour selection in combination with an absolute magnitude limit provides the most effective way of selecting M-dwarfs en masse.

Slides (PDF file) (798.0 KB).

2:15 –2:30 p.m. — Flying the nest to the Magellanic Clouds and Bridge with GALAH and TESS-HERMES
Jeffrey SIMPSON, Postdoctoral Fellow, Australian Astronomical Observatory

We report the serendipitous observation about 560 members of the Magellanic Clouds by the Milky Way spectroscopic GALAH and TESS-HERMES surveys. We also find at least one star that appears associated with structured star formation in the Magellanic Bridge. All the observed stars in the Magellanic Clouds are intrinsically luminous supergiant stars, well outside the normal training set of The Cannon parameter pipeline used by these surveys. But we find that these supergiants are located coherently (if astrophysically incorrectly) in label space, allowing us to identify Magellanic Cloud stars with a very low rate of false positives and negatives. We are able to reject dozens of stars using this label-based criterion that would be identified if simply using proper motions and radial velocities. This work shows the power of data-driven methods, especially in the regime of precise, but inaccurate labels.

Fri, 29 Jun, 2:30 p.m. to 2:45 p.m. Day ↑ | Top ↑

Student Prize Announcement; Closing Ceremony

Location: ATC 101 — Chair: Karl GLAZEBROOK, Swinburne

13:15 - 15:30 Session Recording