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ASA Annual Scientific Meeting 2018 – Posters

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Determining effects of telescope spatial resolution with synthetic observations of galaxy simulationsAyan ACHARYYA, Mr.

How well can we recover metallicity gradient in galaxies, given telescope limitations? We produce realistic synthetic IFU data cubes from Enzo simulations of star forming disk galaxies, by including the effects of telescope resolution and instrumental noise, to understand the observation of metallicity gradients. We conduct a parameter study to specifically investigate the effect of spatial resolution and signal-to-noise ratio (SNR) on inferred metallicity gradient. I will present our new MAPPINGS photoionization models of HII regions and the steps involved to produce the mock data cubes. I will also discuss the results and their implications on the metallicity gradient measurements currently being carried out as part of large IFU surveys like SAMI. We find that, at a given spatial resolution the accuracy of the inferred gradient saturates to a “best possible” value, irrespective of how high the SNR is. The magnitude of this accuracy depends on the true gradient and the metallicity diagnostic used. I will also discuss the effects of imposing a SNR threshold criteria. In future, we plan to use other hydrodynamical simulations with different underlying physics, to generate our mock observations. Comparing the different mock observations with real IFU observations will help us constrain the physical processes in the observed galaxies.

Automated Cross-identification of Wide-area Radio SurveysMatthew ALGER, The Australian National University

Radio host galaxy cross-identification is usually done manually by experts. This will be intractable for large upcoming radio surveys like the Evolutionary Map of the Universe (EMU). Automated cross-identification will be critical for these future surveys, and machine learning may provide the tools to develop such methods. We applied a standard approach from computer vision to cross-identification, sourcing training data from the citizen science project Radio Galaxy Zoo. We used this to cross-identify the $1.4$~GHz Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey with the All\emph{WISE} infrared survey, as well as the $1.4$~GHz Australian Telescope Large Area Survey (ATLAS) with the \emph{Spitzer} Wide-area Infrared Extragalactic (SWIRE) survey. We look at the benefits and challenges of using citizen science like Radio Galaxy Zoo to train machine learning methods for upcoming surveys, and examine the impact of using these complex methods instead of simpler cross-identification rules.

The structure of magnetised thermal plasma in the lobes of Fornax A and Centaurus ACraig ANDERSON, CSIRO

The search for magnetised thermal plasma in radio lobes has a long and storied history, but conclusive detections of this material have remained elusive. Over the past few years, work at radio and X-ray/gamma ray wavelengths has resulted in claimed detections of ~10^10 solar masses of thermal plasma in the lobes of two of our nearest and most iconic radio galaxies --- Fornax A and Centaurus A --- though with poor constraints on its origin and structure. In this talk I will introduce our recent broadband polarisation study of Fornax A, wherein we claim to directly detect and map the detailed magneto-ionic structure of thermal plasma in the lobes, and reveal its likely origin. I will also present new results in the same vein for the radio galaxy Centaurus A, which make use of broadband polarisation data from the new ASKAP telescope.

The QUOCKA survey: A new window on the magnetised environments of AGNCraig ANDERSON, CSIRO

A crucial missing element in our picture of the intrinsic structure and evolution of radio galaxies is the role played by magnetic fields. Newly observed frequency-dependent polarisation behaviours represent a unique and powerful means for studying magnetoionized structure along the line of sight to these sources, but also present significant new challenges for modelling and interpretation. The QUOCKA Survey will enable new progress in this field by generating a broadband polarisation catalog that will enhance, and allow interpretation of, polarimetry surveys from the Square Kilometre Array and its pathfinders for many years to come. Building on the exquisite broadband polarisation performance of the ATCA, and sophisticated techniques for comparison with astrophysical source models, QUOCKA will reveal the detailed internal magnetoionic properties of 250 radio galaxies, and their relationship to other host galaxy properties. In this poster, we describe the survey and its goals, and present early science results.

Investigating black hole formation and natal kicks with VLBI astrometryPikky ATRI, International Centre for Radio Astronomy Research

Stellar mass black holes provide a probe into the deaths of massive stars, including the progenitors of the gravitational wave events detected by LIGO. Even though the first black hole (BH) was detected decades ago, the mechanism by which BHs form is not observationally well constrained. Theoretical models suggest that BHs are born when a massive star dies, either with or without a supernova explosion. BHs born with a supernova explosion get strong natal kicks (similar to but not as high as those received by neutron stars), whereas direct collapse BHs do not incur such a kick. Thus, the natal kick is an indicator of the pathway by which a BH might have formed. We are studying natal kicks imparted to BHs by using stellar mass BH X-ray binaries (BHXBs) as probes. We are measuring the proper motion of the BH systems during their hard states (when their radio emission is compact), and combining this with the radial velocity and distance to the system to get the full three-dimensional space velocity. The system is then traced back in time through the Galactic potential to estimate the magnitude of the natal kick that could have put the binary system into its Galactocentric orbit. We are using the Australian Long Baseline Array, the Very Long Baseline Array in the US, and the European VLBI Network to provide the high-precision VLBI astrometry needed to measure the proper motions (~ few mas/yr) of these BHXB systems. We are also folding into our analysis the few BHXB systems that are optically bright enough in quiescence to be measured by Gaia. Other than giving insights into how a BH is born, the natal kick distribution is a key parameter in determining the number of BHs retained or ejected from globular clusters. Since the probability of a BH-BH binary being formed is higher in globular clusters than in the Galactic field, the natal kick distribution directly affects the predicted rates of BH-BH mergers. In this talk, I will present the natal kick analysis of several BHXB systems and the implication for their formation mechanisms.

Photometric Selection of Lyman Continuum Galaxies: MOSFIRE ObservationsRobert BASSETT, Swinburne

The escape fraction of ionizing radiation from galaxies has a fundamental influence on the intergalactic medium across cosmic time, most notably during reionization. In this talk I will present MOSFIRE observations of z~3 galaxies, photometrically selected for their potential high escape fractions (using the Cooke et al. 2014 method). We examine the emission line properties (e.g. [OII], Hbeta, [OIII]) of selected galaxies in comparison with Lyman Break Galaxies, Lyman Alpha Emitters, and other highly ionised galaxies including those with known ionizing radiation escape. Based on the results of this pilot study, we have considerably improved our methodology in selecting Lyman continuum emitting galaxies for our on-going observations, including direct detection using HST and LRIS.

TeV Gamma-ray Sources in the Galactic Centre: Comparisons to Diffuse Molecular GasRebecca BLACKWELL, The University of Adelaide

The High Energy Stereoscopic System (H.E.S.S.) has recently published new TeV gamma-ray data towards the central 200 parsecs of our galaxy. This region includes several interesting point sources and extended sources, two of which are potentially associated with Cosmic Ray PeVatrons. A comparison is made between these sources, and the new Mopra Central Molecular Zone Carbon Monoxide Survey data.

The Mopra Southern Galactic Plane CO SurveyCatherine BRAIDING, University of New South Wales

The Mopra carbon monoxide (CO) Survey is now in its eighth and final year of science observations of the molecular clouds and gas of the Southern Galactic Plane in the 109–115 GHz J = 1–0 transitions of 12CO, 13CO, C18O and C17O. Its science objectives: (i) to determine where and how molecular clouds are forming in the Galaxy and (ii) to probe the connection between molecular clouds and the ‘missing’ gas inferred from gamma-ray observations. These data have been taken at 0.6 arcminute spatial resolution and 0.1km/s spectral resolution, and the third data release (of 50 square degrees) has just been published on the Mopra CO website and the PASA data store.

The full survey now covers over 200 square degrees of the Galactic plane, from Galactic longitudes l = 255–+11◦ and latitudes |b| ≤ 1.0◦, with extra coverage for regions of interest such as the Central Molecular Zone and the Carina Nebula. We present here a new series of images from the next data release in preparation: velocity-integrated maps, spectra and position-velocity plots that illustrate the Galactic arm structures in unprecedented clarity.

Simultaneous Estimation of Large-Scale Structure and Milky Way Dust Extinction from Galaxy SurveysMatías Andrés BRAVO SANTA CRUZ, ICRAR/UWA

The high cosmological precision offered by the next generation of galaxy surveys requires improved corrections for Galactic dust extinction. We explore the possibility of estimating the dust extinction and large-scale structure simultaneously, making use of the predictable manner in which Milky Way dust affects the number density, median brightness, and median colors of galaxies in a given sky location at all redshifts. To test our method, we use synthetic light cones from cosmological simulations, one designed to model observations from the Dark Energy Spectroscopic Instrument and the other to model those of the Large Synoptic Survey Telescope. At the resolution of ~1°, the models predict a dispersion of the number density and median galaxy properties comparable to typical effects of Milky Way dust, making it feasible to attempt a simultaneous measurement. We introduce a Bayesian formalism that optimizes this approach by combining prior information from emission-based dust maps with the likelihood of Galactic dust extinction determined from the excursion of galaxy properties at each sky location.

Empirical The spectral energy distributions of galaxies and quasarsMichael BROWN, Monash University

Empirical SEDs are often critical for k-corrections, photometric redshifts, star formation rates, exposure time calculations and tests of SED fitting codes. While Coleman, Wu & Weedman (1980) and Kinney et al. (1996) were the benchmarks for galaxy SEDs for many years, over the past decade more SED template libraries have become available covering more galaxy types, with broader wavelength ranges and achieving higher precision. The improvements in SEDs are clearly linked to improvements in spectrophotometry and photometry, including the availability of wide field calibrated imaging (i.e. GALEX, SDSS, 2MASS, Spitzer, WISE). I will demonstrate that we can create good SEDs for individual galaxies and quasars by renormalising spectrophotometry to matched aperture photometry. I will conclude by presenting new SEDs of individual galaxies and quasars spanning from 0.1 to 35 microns (and in some instances 0.1 to 200 microns), and illustrate their utility for photometric redshifts.

Radio mode feedback evolution of HERGs and LERGs in XXL-SAndrew BUTLER, University of Western Australia

The evolution of the comoving kinetic luminosity densities ($\Omega_{\rm{kin}}$) of the radio-loud (RL) high-excitation radio galaxies (HERGs) and low-excitation radio galaxies (LERGs) in the 25 deg$^2$ ultimate XMM extragalactic survey south (XXL-S) field is presented. XXL-S was observed at 2.1 GHz with the Australia Telescope Compact Array (ATCA) and is currently the largest area pre-SKA radio survey to reach the relatively deep median rms noise of $\sigma \sim$ 41 $\mu$Jy beam$^{-1}$. The radio depth, resolution ($\sim$4.8$''$), and wide area of XXL-S, combined with its multiwavelength coverage from X-ray to mid-infrared wavelengths, allowed the construction of the radio luminosity functions (RLFs) of the RL HERGs and LERGs across a wide range in radio luminosity out to high redshift. An optical cut of $M_i < -20$ was applied to the RL HERG and LERG samples to ensure they contained galaxies detectable at all redshifts. The RLFs were then constructed in four redshift bins out to $z=1.3$ using the $1/V_{\rm{max}}$ method. The LERG RLFs display weak evolution, as expected: $\Phi (z)$ $\propto$ (1+$z$)$^{0.59 \pm 0.13}$ in the pure density evolution (PDE) case and $\Phi (z)$ $\propto$ (1+$z$)$^{0.81 \pm 0.22}$ in the pure luminosity evolution (PLE) case. Contrary to previous studies, the RL HERG RLFs demonstrate only slightly stronger evolution than the LERGs: $\Phi (z)$ $\propto$ (1+$z$)$^{0.88 \pm 0.14}$ for PDE and $\Phi (z)$ $\propto$ (1+$z$)$^{1.51 \pm 0.26}$ for PLE.  This result stems from the identification of RL HERGs that are optically and/or radio faint ($M_i > -23$ and/or $S_{\rm{1.4GHz}}$ < 2.8 mJy), which have been excluded from most previous samples. The RLFs and the Cavagnolo et al. (2010) scaling relation were used to calculate the evolution of $\Omega_{\rm{kin}}$ for the RL HERGs and LERGs, which showed that LERGs account for most of the kinetic luminosity output of RL AGN at all redshifts. The $\Omega_{\rm{kin}}$ results were then compared to the predictions from various simulations. The latest prediction for the evolution of radio mode feedback in Croton et al. (2016) is consistent with the $\Omega_{\rm{kin}}$ evolution for all XXL-S RL AGN (all RL HERGs and LERGs), but only if the Willott et al. (1999) scaling relation is used. Simulations that predict the $\Omega_{\rm{kin}}$ evolution of LERG equivalent populations show similar slopes to the XXL-S LERG evolution, implying a consistency between observations of LERGs and models of radiatively inefficient accretion. On the other hand, only the Mocz et al. (2013) simulation, which featured a constant radio AGN duty cycle of 0.1, predicted an $\Omega_{\rm{kin}}$ evolution for the RL HERG equivalent population that is consistent with the XXL-S RL HERG evolution. The relatively weak evolution of the XXL-S RL HERGs and its lack of correspondence to most simulations implies that radiatively efficient accretion of cold gas onto supermassive black holes since $z = 1.3$ results in a higher abundance of AGN that exhibit radio mode feedback than has been previously found or predicted.

The HI Velocity Function: A test of Cosmology or Baryon physics?GARIMA CHAUHAN, International Centre for Radio Astronomy Research, University of Western Australia

Atomic Hydrogen (HI) plays an important role in galaxy formation and evolution. HI is mainly detected by its emission at the radio wavelength of 21 cm, from which we can get fundamental information of galaxies, such as their rotational velocity and HI mass content. Past blind surveys, such as ALFALFA and HIPASS have provided the first reliable measurements of the HI mass and velocity functions. The latter is of particular interest as it has been claimed to be in significant tension with the predictions from LCDM. In this project, we model the HI emission lines of the galaxies in the semi-analytic model GALFORM, built on the Millennium-II simulation and create an ALFALFA mock survey with all the observational features of the real ALFALFA survey. We use this mock to understand how the HI velocity width traces the dynamical mass of galaxies, and test whether the reported discrepancies between the measurements and simulations are due to intrinsic limitations of our standard cosmological model or due to the complexity of baryonic physics.

Clustering of rotational glitches in the Crab pulsarJulian CARLIN, The University of Melbourne

The Crab pulsar has had 21 stochastic, spin-up events ("glitches") in the last 36 years of observation, interrupting an otherwise monotonic decrease in rotation rate. The distribution of inter-arrival waiting times between glitches appears to fit a homogeneous rate Poisson process. However models with an inhomogeneous rate provide a better fit to the data when the time-ordered nature of the waiting times is considered. If the glitches are modelled as a homogeneous Poisson process there are signs of clustering at a $2\sigma$ level, when testing with Ripley's $K$ function.

Low-frequency radio studies of X-ray binary jetsJaiverdhan CHAUHAN, 1 Turner Avenue, Technology Park, Bentley, WA, 6102

Most objects in the Universe, from young stellar objects, accreting white dwarfs (WDs), neutron stars (NSs) and stellar-mass black hole (BHs) through to the supermassive BHs at the centres of galaxies, grow in mass via the process of accretion. Accreting NSs and stellar mass BHs, known as X-ray binaries (XRBs), allow us to study the connection between accretion and ejection as they evolve on humanly observable time scales. XRBs also present excellent laboratories to explore relativistic and energetic phenomena such as radio jets. Until recently, the lack of sensitive low-frequency radio instruments has prevented detailed studies of XRB radio jets below 1 GHz, limiting our knowledge of that regime. Low-frequency radio observations can provide insights into open questions such as the role of feedback from jets on the environment of XRBs and the absorption properties of the surrounding media. We are using observations from the Murchison Widefield Array (MWA) to determine how the radio flaring seen at GHz frequencies translates to the low-frequency regime. We have recently used the MWA to observe two newly detected XRBs in outburst; MAXI J1535-571 and MAXI J1820+070. For these two systems we are studying the behaviour of the low-frequency radio spectrum, to constrain the low-frequency properties of XRB radio jets. We report our preliminary results in this poster.

Radial Migration & GALAHKhalil CHEIKH-HUSSEIN, UNSW

Radial migration, a crucial piece of the puzzle that is disk galaxy evolution, has been the topic of significant theoretical study in recent years. We use data from the GALAH (Galactic Archaeology with HERMES) survey (Buder et al. 2018) to investigate observational evidence for radial mixing in the metallicity distribution function (MDF) in the disk. Similar to Hayden et al. (2015), we track the MDF across 3<R<15 kpc in Galactic radius. We measure a radial variation in the MDF that is broadly consistent with the theoretical predictions of Roksar et al. 2008 and Loebman et al. 2016.

Simulating the Thermal Memory of ReionisationJames DAVIES, the University of Melbourne

We introduce a post-processing temperature model for the Dark-ages, Reionisation And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project in order to calculate the thermal state of the intergalactic medium during the Epoch of Reionisation (EoR). Using the ionising background and density field from the semi-analytic galaxy model Meraxes, we predict the thermal histories of the IGM for a range of reionisation histories and parameters. We show that temperature is highly correlated with the redshift of reionisation shortly after the universe is ionised. However as the IGM cools, memory of the redshift of reionisation is lost, and a power-law temperature-density relation is formed with a slope γ-1 ≈ 0.5, in agreement with previous work. We demonstrate how the nature of ionising sources and structure of intermediary absorbers affect the temperature history of the IGM, and show how we can constrain the nature of the EoR by comparing these new outputs to observational data.

Black Hole Mass Scaling Relations for Spiral Galaxies Determined from Pitch Angles and Multicomponent Structural DecompositionsBenjamin DAVIS, Swinburne University of Technology

In an effort to derive accurate bulge magnitudes for the current full sample of 43 spiral galaxies with directly measured supermassive black hole masses, we have analysed their images and light profiles in exquisite detail. We found that it was important to account for not just the bars, but also the rings and partial rings, i.e. ansae, at the ends of these bars. We have additionally performed a careful measurement of the spiral-arm “pitch angles” for these galaxies. This has enabled us to revise the black hole scaling relations for spiral galaxies, using more accurate measurements than ever before, and with a sample size which is double that of previous works. A symmetric Bayesian analysis finds $\log\left(M_{\rm BH}/{\rm M_{\sun}}\right)=\left(2.22_{-0.27}^{+0.32}\right)\log\left(M_{\rm *,sph}/4.0\times10^{10}\,{\rm M_{\sun}}\right)+(7.24_{-0.12}^{+0.11})$. This reinforces previous observational studies and several simulations, which have shown a near-quadratic slope at the low-mass end of the $M_{\rm BH}$--$M_{\rm *,sph}$ diagram. The non-linear slope additionally rules out the idea that many mergers, coupled with the central limit theorem, produced this scaling relation, and it has important implications for the formation pathway of supermassive black holes.

A Major Upgrade of the Pierre Auger ObservatoryBruce DAWSON, University of Adelaide

The Pierre Auger Observatory covers an enormous 3000 square kilometre area in western Argentina and studies the most energetic particles known in the Universe, the highest energy cosmic rays. The Observatory is currently undergoing a major upgrade to enhance its capabilities for identifying the masses of the particles, and to extend its lifetime for another decade. Before describing the motivation for the upgrade and its current status, I will review a few of Auger's many scientific highlights to date, including surprising results about the masses of the highest energy particles, and the first unambiguous measurement by any observatory of extra-galactic cosmic rays.

UTMOST-2D: Upgrading the Molonglo Radio Telescope to Localise Fast Radio Bursts in 2DCherie Kathleen DAY, Swinburne University of Technology

At the cm wavelengths at which Fast Radio Bursts (FRBs) have been detected, associating a FRB with a single host galaxy requires an interferometer capable of real-time localisations with ~arcsecond spatial resolution (i.e. one with an extent of a kilometre or more) in two dimensions. These localisations, achievable with UTMOST-2D, will greatly enhance our understanding of FRBs and should yield answers to several outstanding questions in the field, beyond that of other existing or in-development instruments. Designing a highly sensitive, wide field-of-view, low-cost receiver system on an interferometer is challenging but critical in the effort to achieve the required localisations during blind searches and probe the faint and bright ends of the FRB brightness distribution. Thus, a complete upgrade to the receiver system on the currently dormant North-South arm of the Molonglo Radio Telescope is underway and being commissioned, with very promising early results. These instrumentation innovations will be widely applicable across radio astronomy and, thus, create a foundation for future low-cost, high sensitivity instruments, facilitating the achievement of science goals with a smaller budget.

Radio follow-up of gravitational wave events with Australian Radio TelescopesDougal DOBIE, University of Sydney

Our understanding of neutron star mergers has drastically increased as a result of observations of the first detected neutron star merger, GW170817, but similar follow-up of a larger sample of events is required to understand their typical brightness, timescale and spectral behaviour. This will determine whether GW170817 was a standard merger, or something exceptional. We also expect to detect neutron star-black hole mergers in the upcoming LIGO observing run (O3, starting in November), and radio observations will provide vital constraints on the energetics and geometry of any new type of event. This poster will discuss our plans for follow-up of future events with the Australia Telescope Compact Array (ATCA) and the Australian Square Kilometre Array Pathfinder (ASKAP). The ATCA will be useful for detecting events like GW170817 which was quite well-localised and had an optical counterpart detected within hours. Due to its wide field of view, ASKAP will be more suited to detecting long-term radio emission from poorly localised events (hundreds of square degrees) with no detected electromagnetic counterpart, and is also capable of detecting prompt radio emission produced in the late stages of neutron star mergers. Our follow-up strategy is also applicable to other forms of transients, including short gamma-ray bursts.

Dissecting the Outflows of NGC5728Mark DURRÉ, Swinburne University of Technology

The VLT IFU spectrographs SINFONI and MUSE, plus other multi-messenger observations, explore the complex nuclear structure of the Seyfert 2 galaxy NGC5728. The AGN is driven by a SMBH of ~2.3 x 10^8 M_sun, at an Eddington ratio of 0.005, accreting 2.7 x 10^-2 M_sun/yr. The outflow kinetic power is 1% of the AGN bolometric luminosity. The kinematic analysis of the massive biconal outflows (~40 M_sun/yr) shows that a significant fraction of the nuclear gas available for star-formation is expelled over an assumed active lifetime of 10 Myr. The AGN Unified Model is supported by the orientation and opening angle of the outflows, the obscuring dusty bar and the Seyfert classification. The outflows (extending over 2.5 kpc from the AGN) are traced by shocked [Fe II] emission, with an extended coronal-line region revealed by [Si VI] excited by X-rays and shocks. A molecular hydrogen disk (~6 x 10^8 M_sun) is spatially and kinematically distinct from the outflows, and is excited mainly by thermal processes to 1400-2000 K. The outflows are also traced by X-ray and radio jets, with radio images also revealing SN remnants in the SF ring.

Gas-rich group galaxiesRobert DZUDFZAR, Swinburne University of Technology

Galaxy groups are the most common environment in the local Universe, thus it is crucial to understand how galaxies evolve within such structures. I will present HI analysis of 9 nearby gas-rich galaxy groups that have 4 or more group members. The HI imaging of these galaxy groups were obtained using Australia Telescope Compact Array and Very Large Array. Preliminary results show that the majority of the HI content is concentrated in the central, the most massive galaxy in a group. These central galaxies tend to larger gas-mass fraction, than the galaxies of the same size in isolation, and have large HI disk diameters. I will discuss about the possible gas buildup onto the central galaxies in the group environment.

The Data Mining Guide to the Galaxy and BeyondSabrina EINECKE, The University of Adelaide

The Large Area Telescope (LAT) on board the Fermi satellite conducted the deepest all-sky survey in gamma rays so far. Despite outstanding achievements in assigning source types, a large number of sources in the Third Fermi-LAT Source Catalog (3FGL) remains without plausible associations, or is associated to blasars of uncertain type. Previous machine learning strategies to assign source types were based solely on properties extracted from gamma-ray observations. The extension to multi-wavelength information provides additional source type-specific characteristics for a better classification. At the same time, it offers the possibility to determine the most likely corresponding counterpart. In this contribution, the novel wavelength-dependent machine learning method is described, and the results of its application are discussed. Furthermore, this investigation serves as a proof of concept for source and counterpart associations of future Big Data experiments like the Cherenkov Telescope Array (CTA) or the Square Kilometre Array (SKA), where conventional methods are no longer sufficient.

Reconciliation of Big Bang Nucleosynthesis with the quantum theory of dark matterAllan David ERNEST, Charles Sturt University

The existence of gravitational quantum states is well established [1]. Ernest [2,3,4] has shown that, in the deep gravity wells of galaxy and cluster halos, there exist many such gravitational eigenstates, most of which are long-lived, stable, and extremely weakly interacting with photons. These “gravitational Rydberg states” lead to a natural understanding [4,5] of dark matter: the dark components of galaxy halos are simply composed of “dark baryons”, baryons whose gravitational eigenspectral ensembles can be shown to frequently contain a large percentage of these dark states. Such baryons will have scattering cross sections remarkably lower than what would be expected from lab-based measurements or theoretical calculations based on localized particles. There is however a serious obstacle to such a proposal - two pillars of evidence that lead to the conclusion that dark matter cannot be baryonic: (1) the predictions of Big Bang Nucleosynthesis, and (2) observations of the cosmic background anisotropy. How then does the quantum theory of dark matter achieve consistency with these two issues? In this presentation I will deal with the first issue: how does the quantum theory of dark matter enable a universe with a baryonic fraction > 5% of the closure density to be reconciled with BBN? [1] V V Nesvizhevsky et. al., Nature, 415, 297-9, 2002 [2] A. D. Ernest, in Proceedings of IAU Symposium 220, “Dark Matter in Galaxies”, 21-25 July 2003, Sydney, Australia, Eds. Ryder et al, (San Francisco:ASP) ISBN 0-521-84803-2, July 2004 [3] A. D. Ernest, J.Phys.A:Math.Theor., 42:115207/115208, 2009 [4] A. D. Ernest, in “Dark Matter: New Research”, editor J. Val Blain, NOVA Science Publishers, (New York) ISBN: 1-59454-549-9, 2006 [5] T. A. Whinray and A. D. Ernest, Gravit. Cosmol. 24: 97, 2018 https://doi.org/10.1134/S0202289318010152

FRB Microstructure revealed by the real-time detection of FRB170827Wael FARAH, Swinburne University of Technology

Fast Radio Bursts (FRBs) form a new class of radio transients, with approximately 30 published detections since 2007. These bright, millisecond-wide pulses still defy explanation, where over 20 progenitor models have been put forward in an attempt to explicate their origin. All but one of these bursts haven't been observed to repeat. The measured electron column density along their lines of sight significantly exceed the expected contribution from the Milky Way, hinting at an extragalactic origin. Thus, FRBs promise to provide possible insights into new physics and valuable probes of the intergalactic medium. UTMOST is a project that is transforming the 50+ year old Molonglo Observatory Synthesis Telescope into an FRB finding machine. This facility has not only delivered the first interferometric detection of FRBs, but has discovered interesting events such as FRB170827. The real time detection of this particular FRB has triggered a voltage capture i.e. the recording of the amplitude and phase of the incident electromagnetic radiation. Analysis of the voltage data has revealed discernible spectral and temporal micro-structure that would not have been otherwise observed. In my talk, I will present an overview of the UTMOST project, focussing on the FRB search programme and the recent results from the analysis of FRB170827.

Unpicking Galaxy Dynamics and Large Scale Structure in the Early Universe using Observed Lyman-alpha RelationshipsGarry FORAN, Swinburne University of Technology

The potential utility of Lyman-alpha (Lya) to elucidate the mechanisms of galaxy evolution in the early universe is tantilising.  However, teasing out the details of direct causal relationships between Lya and specific galactic properties has been notoriously difficult.  Nevertheless, several relationships between Lya equivalent width (EW) and the properties of z~3 galaxies have been established with various significance, e.g., relationships with ISM line strength, UV continuum slope, gas outflows, morphology, and galaxy clustering behaviour on small and large scales.

I will present two aspects of our work in which we are statistically exploring the relationships between
Lya and more than 10 different intrinsic and extrinsic properties of high redshift Lyman break galaxies (LBGs), with the aim of constructing a coherent observation-based picture of galaxy evolution to test
against predictions by modern cosmological simulations.
Firstly, I will present our results that show a direct correlation between Lya EW and galaxy kinematics for
z ~ 2 and z ~ 3 LBGs.  Even with the relatively small sample currently available,
it is clear that LBGs with Lya dominant in absorption (aLBGs) tend to be disc-like (rotating) and that LBGs with Lya dominant in emission (eLBGs) tend to be dispersion-dominated or non-rotating; a result that is consistent with the same relationship reported recently for high-redshift galaxy analogs in the local Universe.  Secondly, I will show how our exploration of the relationship between Lya EW
and the large-scale spatial distribution of LBGs has revealed
a difference in the clustering behaviour of aLBGs and eLBGs that is indicative of
the morphology-density relationship observed in the modern-day Universe.

All-sky radiometer for narrowband gravitational waves using data foldingBoris GONCHAROV, Monash University

Discovery of continuous gravitational radiation is among the most scientifically interesting prospects for the LIGO-Virgo collaboration. We present a method for detecting persistent gravitational waves lasting days-months using radiometry and cross-correlation of strain data from LIGO antennae in Hanford and Livingston. Models predict this radiation to originate from neutron stars where non-zero quadrupole moment of inertia is sustained due to internal deformations or accretion from a companion star. Most importantly, this work yields a robust all-sky search sensitive to other, yet unknown sources, as it works with only minimal assumptions about the waveform. Such exotic scenarios may include black hole interaction with an unknown bosonic field. Another feature of this method is employment of a symmetry of signal pattern repetition for every sidereal day. This technique, folding, solves a computational problem of previous radiometer searches, making the all-sky all-frequency radiometer search possible. We demonstrate an end-to-end analysis using the Monte-Carlo noise at the level of LIGO design sensitivity. We discuss treatment of instrumental artifacts using LIGO's time-shifted O1 data, and project a strain amplitude sensitivity of the search for LIGO's O1 run.

An all-sky radiometer for narrowband gravitational waves using data foldingBoris GONCHAROV, Monash University

Discovery of continuous gravitational radiation is among the most scientifically interesting prospects for the LIGO-Virgo collaboration. We present a method for detecting persistent gravitational waves lasting days-months using radiometry and cross-correlation of strain data from LIGO antennae in Hanford and Livingston. Models predict this radiation to originate from neutron stars where non-zero quadrupole moment of inertia is sustained due to internal deformations or accretion from a companion star. Most importantly, this work yields a robust all-sky search sensitive to other, yet unknown sources, as it works with only minimal assumptions about the waveform. Such exotic scenarios may include black hole interaction with an unknown bosonic field. Another feature of this method is employment of a symmetry of signal pattern repetition for every sidereal day. This technique, folding, solves a computational problem of previous radiometer searches, making the all-sky all-frequency radiometer search possible. We demonstrate an end-to-end analysis using the Monte-Carlo noise at the level of LIGO design sensitivity. We discuss treatment of instrumental artifacts using LIGO's time-shifted O1 data, and project a strain amplitude sensitivity of the search for LIGO's O1 run.

Reproducible research: software, methodology, and containersPaul HANCOCK, Curtin University

The publication of a paper is typically seen as the final output of a research project, especially by grant agencies. The reality is that the results are not reproducible or verifiable unless the data, software, and methodology are also published. In this talk I will discuss the how and why of reproducible research. In particular I will focus on the publication of data, software, and methodology. The core messages will be: how to publish these resources so that they can be used by others; how to gain recognition for these contributions; and equally as important, how to find and use existing resources and give credit appropriately. I will draw on my own experiences with the development and publication of the Aegean software, to show the benefits and pit-falls of publishing 'non-standard' outputs. [This talk is intended for the computing focused special session proposed by ADACS]

GLEAM-X: GaLactic and Extragalactic All-sky MWA Survey -- eXtendedNatasha HURLEY-WALKER, Curtin University

Following the success of the original Murchison Widefield Array (MWA) flagship survey, the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, we have successfully proposed for observations of a follow-up survey using the new extended baselines of the upgraded MWA. This will increase the survey resolution by a factor of two, its depth by an order of magnitude, and greatly enhance its scientific utility. The original survey has provided astronomers across the world with a wealth of information on colliding galaxy clusters, young and dying radio galaxies, and the energetics of our Milky Way galaxy. With this extension we will push back to higher redshifts, disentangle the complex morphology of unusual sources found in GLEAM, and better explore the polarised universe.

The CSIRO ASKAP Science Data ArchiveMinh HUYNH, CSIRO / ICRAR

Astronomy is moving into the era of “big data”, a paradigm where data volumes will be reaching 10s PBs (ASKAP), and in the near future 100s PBs (SKA1). Science from the next generation of radio telescopes requires long term storage of the data and tools for querying and accessing the data. CSIRO IM&T and CASS have addressed this by building the CSIRO ASKAP Science Data Archive (CASDA) to provide long term storage for Australian SKA Pathfinder (ASKAP) data products, and the hardware and software facilities that enable astronomers to access the data. CASDA will store ~5 PB per year from ASKAP and serve that to astronomers around the world using both virtual observatory (VO) and web-based portal services. I will present the current status of CASDA, discuss its functionality, and outline future development plans.

Hybrid Calibration: a holistic approach to the calibration of the next generation of radio telescopesRonniy JOSEPH, ICRAR - Curtin University

Driven by the needs of the Epoch of Reionisation experiment we are constructing the largest radio telescopes in the world, e.g. the recently expanded Murchison Widefield Array (MWA and the Square Kilometre Array (SKA). However, these new facilities require calibration with an unprecedented accuracy and precision. In this talk I will outline our approach to a holistic calibration framework, that encodes our knowledge and ignorance about the sky and our instrument. This framework relies on statistical models describing the precision of our knowledge, and I will show how these models will yield us the accurate and precise calibration solutions required in our quest for the first stars in the Universe.

A tale of two spiral galaxiesVirginia KILBORN, Swinburne University of Technology

I will present a multi-wavelength analysis of the J1051-17 galaxy group, which contains two intriguing galxaies: whilst both galaxies have approximately the same stellar mass and star formation rate, their neutral hydrogen (HI) content is vastly different, with one galaxy containing more than ten times the HI mass of the other. The potential reasons for this discrepancy are discussed, along with broader implications on generalised galaxy scaling relations.

Holistic spectroscopyJanez KOS, Sydney Institute for Astronomy, The University of Sydney

Success of galactic archaeology relies on the precision with which we can measure stellar parameters and abundances of chemical elements. At the same time the galactic archaeology surveys are using wide-field, multi-fibre spectrographs to study as many stars as possible. Due to very complicated optics such instruments are prone to optical aberrations the reduction techniques are not made to cope with. This has a significant impact on the science we are able to do within large spectroscopic surveys. I will present a new approach to spectroscopic reduction where we first probe the optical aberrations to a great precision with a photonic comb. This information is then used to forward model the whole image from one dimensional template spectra. We recently demonstrated on Solar spectra that the method is feasible and produces better results than a traditional reduction and spectral extraction. Most notable is more than 2x improvement in resolution, as the forward modeling approach is also an efficient deconvolution algorithm. We are adopting the method to reduce and analyze stellar spectra in the GALAH survey, making it the first such project to benefit from the improved precision of stellar parameters and abundances of chemical elements.

The Cosmic Optical Background from VISTA VIKINGSoheil KOUSHAN, International Centre for Radio Astronomy Research

The extragalactic background light (EBL) is defined as the total flux received today from all sources of photon production since the epoch of recombination. These photons have been produced by stars, galaxies, cosmic rays, active galactic nuclei (AGN), synchrotron emission and dust, all of which arise from the entire path length of the Universe. Understanding this form of energy is essential in astronomy as it encodes all energy production pathways.

In this work, we will compare our results obtained by the integrated galaxy count (IGL) method which sums the photon filled from discrete sources to that measured from very high energy (VHE) astrophysics, which samples all photons. Generally, VHE methods investigate the strong residual emission, which emanates from distant blazars. These high-energy photons are attenuated by interactions between the blazar Tev and EBL micron photons as they pass through the Universe. A comparison between our measurements and the total EBL from VHE experiments represents the fraction of photons arising from diffuse components (light between galaxies) in the Universe.

Currently the uncertainties between these two methods are about 20%, of which the most dominant error is caused by cosmic variance. Adding wide and deep data such as the European Southern Observatory's (ESO) VISTA VIKING data set covering ~1300 deg2 of the Galactic sky are essential to reducing this error component. For this reason, we utilise ProFound, a new source finding package built in R, in order to identify sources and extract photometry from a target image. Running ProFound is computationally expensive and requires multiple iterations. Therefore, we produced our big data set by the supercomputers from the Pawsey supercomputing system in order to optimize it. Using this data set, we aim to reduce this error from cosmic variance down to 5%.

Bringing gravitational waves to the massesPaul LASKY, Monash University

The scientific potential of gravitational-wave astronomy is only limited by one's imagination! Oh, no, wait. It's also limited by the availability and usability of software tools that enable the science. I will present a new tool for enabling gravitational-wave and non-gravitational-wave professionals alike to do gravitational-wave science with a minimal learning curve. The open-source software can be used to detect and analyse existing signals in real LIGO data, as well as inject fake signals into fake data to understand the scientific potential of future observations and future gravitational-wave instruments.

On the formation of the isolated HI cloud GEMS_N3783_2Caleb LAU, Swinburne University of Technology

Using data from the Australia Telescope Compact Array (ATCA) an area of approximately 1.1 by 0:72 degrees surrounding NGC3706 was surveyed for Hi radio emissions. The previously detected GEMS_N3783_2, ESO 378_G 003 and a new galaxy‘ N3783_New’ were found at approximately equal distances away from NGC3706. The closest Hi rich neighbour to GEMS_N3783_2 being the spiral type galaxy ESO 378_G 003 at a projected distance of approximately 460 kpc. The area was surveyed in an attempt to find HI that could give rise to a formation scenario for GEMS_N3783_2, however no additional HI was found. From distances and objects present in the system (a cloud, a HI rich galaxy and a central elliptical), a ring type formation scenario is suggested. Other scenarios such as a low surface brightness galaxy and tidal debris seem unlikely due to the morphology and position of the cloud.

Dark Matter StreamsGrace LAWRENCE, Swinburne University of Technology

The nature of Dark Matter is one of the largest mysteries within the cosmological standard model. New hydrodynamical simulations allow the distribution of dark matter and its interaction with galaxy formation processes to be simulated to greater resolutions than ever before, helping to constrain its properties. Using high-resolution zoom-in cosmological simulations of Milky-Way type galaxies from the GIMIC series (Galaxies-Intergalactic Medium Interaction Calculation), we aim to determine if small-scale dark matter structures persist in galaxy realisations, gaining insight into the potential distribution in real galaxies. By sampling dark matter populations and implementing a series of frame transformations, we explore frame-dependent velocity distributions in an effort to constrain parameter space for Earth-based direct detection experiments. These velocity distributions affect the expected flux and subsequent count rate estimations for experiments like SABRE (Sodium-iodide with Active Background REjection), which will use radio-pure Sodium-iodide crystals to search for the postulated nuclear recoils arising from collisions between the NaI and dark matter nuclei.

New insights into the origin of the blue main sequence in NGC 1850Chengyuan LI, Dept of Physics & Astronomy, Macquarie University

Recent discoveries of bimodal main sequences (MSs) associated with young clusters (with ages 1 Gyr) in the Magellanic Clouds have drawn a lot of attention. One of the prevailing formation scenarios attributes these split MSs to a bimodal distribution in stellar rotation rates, with most stars belonging to a rapidly rotating population. In this scenario, only a small fraction of stars populating a secondary blue sequence are slowly or non-rotating stars. In this talk, I will introduce our latest results about the radial behaviour of the blue MS stars in the young massive cluster NGC 1850. We compare the cumulative number fraction of the observed blue-MS stars to that of the high-mass-ratio binary systems at different radii. The cumulative distributions of both populations exhibit a clear anti-correlation. We suggest that our observations are consistent with the possibility that blue-MS stars are low-mass-ratio binaries, and therefore their dynamical disruption is still ongoing.

Measuring Eccentricity in Binary Black Hole Inspirals with Gravitational WavesMarcus Edward LOWER, Monash University

When binary black holes form in the field, it is expected that their orbits circularize before coalescence. Systems formed through dynamic processes may retain significant orbital eccentricity in the final few orbits prior to merger. If the eccentricity is large enough, these systems will be distinguishable from their quasi-circular counterparts using gravitational-wave data from advanced detectors. We present a framework for performing Bayesian parameter estimation on eccentric black hole inspirals, which we use to determine the minimum possible eccentricity that can be distinguished during the inspiral phase of a binary black hole merger event. We compare the results from this framework with calculations based on the mismatch between eccentric and quasi-circular waveforms. We discuss how measurements of eccentricity can be used to infer the population properties of binary black holes.

Machine Learning Techniques to Increase Lyman Break Galaxy Classification AccuracyLily MARTIN, Swinburne

Recent years have seen the advancement of machine learning methods across all scientific fields. In the age of big data, the use of machine learning is becoming a necessity in order to increase accuracy, and reduce human expenditure. Using data on the Chandra Deep Field South collected by the Dark Energy Survey (DES), and 30-band photometric redshifts including deep, medium-bandwidth infrared generated by the FourStar Galaxy Evolution Survey (ZFOURGE), we applied machine learning strategies to classify Lyman Break Galaxies (LBGs). Up till now, the traditional template-based classification techniques that incorporate coarse criteria in the colour-colour plane, have been used to identify LBGs. The implementation of machine learning to identify LBGs will ideally lead to greater accuracy, by providing a more comprehensive and dynamic inclusion, and reducing the fraction of lower redshift galaxy inclusion when compared to classical techniques.

Searching for OH megamasers in ASKAP early science dataShannon MELROSE, University of New South Wales

OH megamasers are large collections of hydroxyl molecules that encircle the centres of distant, luminous infrared galaxies. They are a powerful probe of the masses of black holes at the centres of these galaxies. We are using ASKAP radio continuum data to conduct a search for OH megamasers in the thousands of galaxies observed. Previous OH megamaser surveys have been restricted in their effective observing frequencies by the local RFI environment. With a frequency coverage from 700 MHz to 1.8 GHz, and situated in a protected radio quiet zone, ASKAP offers an excellent opportunity to search for OH megamasers at substantial redshifts. The results will lead to a better understanding of the growth of supermassive black holes throughout the history of the universe.

Constraining the IMF using HST images of nearby galaxiesGerhardt MEURER, International Centre for Radio Astronomy Research, University of Western Australia

The colour magnitude diagram (CMD) of young resolved stellar populations is degenerate - the distribution of stars depends on both the Star Formation History (SFH) and the Initial Mass Function (IMF) of the stellar populations sampled. The standard approach the community has taken is to assume a canonical IMF and solve for the SFH. Here we adopt the lesser used approach, of assuming a likely constant SFH and solving for the IMF. We employ this approach in a variety of nearby galaxies, concentrating especially on low surface brightness regions. We find that in low surface brightness galaxies and galaxy outskirts that the IMF is suppressed in high mass stars compared to the canonical Kroupa IMF. This result is consistent with findings using integrated H-alpha and UV fluxes, but using completely different techniques. I will present the work of our team, and the merits of our approach.

Abundance Distribution of 47 Tuc with GALAH SurveyMohd Hafiz MOHD SAADON, The University of New South Wales

The goal of the GALAH (Galactic Archaeology with HERMES) survey, being carried out at the Anglo-Australian Telescope, is to explore the history of the Milky Way's formation and evolution using high resolution (R~28,000) spectra of up to 1 million stars. Globular cluster stars were observed in early stages of GALAH as well-studied literature targets, but they are also systems with complex populations that are difficult to explain with current cluster formation models. Using GALAH stellar parameters and abundance data for red giant stars in the relatively metal-rich globular cluster 47 Tuc, I will compare the observed distribution of abundances in different nucleosynthetic families to literature values, and discuss the implications for multiple stellar populations in globular clusters.

Cosmological birefringence forecast for upcoming CMB experimentsBryce MURPHY, University of Melbourne

Cosmological birefringence is predicted by some theories, such as cosmological pseudo-scalar condensate, Lorentz invariance violation and CPT violation etc., and may also be induced by Faraday rotation if primordial magnetic fields are created in the early Universe. Measurements of the polarisation of the cosmic microwave background (CMB) are one way to set limits on the existence of cosmological birefringence from any source. Here we present a 4-point estimator for the rotation angle power spectrum, and discuss how well future CMB experiments can constrain potential parity-violating physics and primordial magnetic fields in the early Universe.

Does Angular Momentum regulate HI gas in isolated Spirals?Chandrashekar MURUGESHAN, Swinburne University of Technology

\documentclass[a4paper]{article} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \def\h1{H\,{\sc i}} \begin{document} \pagenumbering{gobble} The neutral atomic hydrogen (\h1) content of spiral galaxies has been observed to vary with environment, with more \h1-poor or \h1-deficient spirals being observed in high density environments. This has been attributed to influences such as ram pressure stripping and tidal interactions, which remove neutral hydrogen (\h1) from the galaxies. However, some isolated spirals have also been observed to have relatively low \h1 mass fractions. The low densities of the Intra Galactic Medium in isolated environments make ram pressure stripping and tidal interactions unlikely candidates of gas removal. What then could be making some isolated spirals \h1 poor? Recently, Obreschkow et al. introduced the $f_{\textrm{\h1}} - q$ relation ($f_{\textrm{\h1}}$ is the \h1 mass fraction of a galaxy and $q$ is the global stability parameter), where they find a tight positive correlation between the two parameters among isolated disk galaxies. The $q$ parameter is directly linked to the specific angular momentum of the galaxy. The theoretical prediction is that this should be applicable to both \h1 excess and \h1 deficient disk galaxies. If this were to be true, then the \h1 deficiency in galaxies that reside in loose groups and fields can be explained not necessarily due to any stripping mechanisms but due to their low specific angular momentum. In order to verify this, we obtained high resolution \h1 data from the ATCA for 6 \h1 poor isolated spirals. In my talk, I will present the main results which indicate that our sample of \h1 deficient galaxies consistently follow the $f_{\textrm{\h1}} - q$ relation. This result brings to light the importance of angular momentum in understanding the formation history of galaxies. \end{document}

DUST-GAS SCALING RELATIONS AND OH ABUNDANCE IN THE GALACTIC ISMVan Hiep NGUYEN, Macquarie University

Observations of interstellar dust are often used as a proxy for total gas column density N(H). By comparing Planck thermal dust data (Release 1.2) and new dust reddening maps from Pan-STARRS 1 and 2MASS (Green et al. 2018), with accurate (opacity-corrected) HI column densities and newly-published OH data from the Arecibo Millennium survey and 21-SPONGE, we confirm linear correlations between dust optical depth tau353 , reddening E(B−V ) and the total proton column density N(H) in the range (1–30)×10^20 cm^(−2) , along sightlines with no molecular gas detections in emission. We derive an N(H)/E(B−V ) ratio of 9.4×10^21 cm^(−2) mag^(−1) for purely atomic sightlines at |b|>5◦, which is 60% higher than the canonical value of Bohlin et al. (1978). We report a ~40% increase in opacity sigma353 = tau353 /N(H), when moving from the low column density (N(H) <5×10^20 cm^(−2)) to moderate column density (N(H) >5×10^20 cm^(−2) ) regime, and suggest that this rise is due to the evolution of dust grains in the atomic ISM. Failure to account for HI opacity can cause an additional apparent rise in sigma353, of the order of a further ~20%. We estimate molecular hydrogen column densities N(H2) from our derived linear relations, and hence derive the OH/H2 abundance ratio, X(OH) for all molecular sightlines. The X(OH) ratios derived from the two N(H) proxies are consistent, with a mean value of ~1×10^(−7) . Our results show no evidence of systematic trends in OH abundance with N(H2) in the range N(H2) ~(0.1−10)×10^21 cm^(−2). This suggests that OH may be used as a reliable proxy for H2 in this range, which includes sightlines with both CO-dark and CO-bright gas.

The Cool Circumgalactic Medium in Group EnvironmentsNikki NIELSEN, Swinburne University of Technology

The baryon cycle is key to understanding the observed global properties of galaxies and plays a large part in governing galaxy evolution. Signatures of the baryon cycle such as accretion from the cosmic web and stellar-driven outflows are best probed in gaseous halos surrounding galaxies, i.e., the circumgalactic medium (CGM), which is a reservoir with a gas mass comparable to that within galaxies and extends out to ~300 kpc. Extensive work has gone into characterising these CGM gas flows in isolated galaxies using absorption in the spectra of background quasars. Cool (10^4 K) gas traced by MgII doublet absorption is commonly associated with outflows and recycled accretion, where gas kinematics and absorption strengths are larger for outflowing gas. However, little work has been done to characterise the CGM in group environments, where other processes such as tidal stripping due to galaxy interactions may contribute to the observed CGM properties. Using ~30 MgII absorbers associated with group environments at z~0.5, we compare group CGM kinematics and absorption properties to those of the well-studied isolated CGM to quantify the effect that interactions have on the baryon cycle.

data central for AstronomersSimon O'TOOLE, Australian Astronomical Observatory

data central is the AAO's flagship virtual observatory service, providing a central repository for AAT and UK Schmidt observations, survey-team derived data products and documentation. The system brings together catalogues, imaging, spectra and data cubes from dozens of surveys, providing an intuitive interface to query, explore and cross-match data sets of national and international significance. We briefly introduce the current services data central offers to help astronomers familiarize themselves with the system, including: the cutout (access imaging data from some of the world's leading facilities to quickly explore sources of interest and produce publication quality images), query (extends the existing functionality of the TAP server and now makes the catalogues hosted at data central queryable via the web interface), schema (browsing the survey-team generated metadata), documentation and cloud services. Finally we'll present the timeline for future datasets and milestones for data central.

Polarimetry of 1720-MHz OH masers.Chikaedu OGBODO, Macquarie University

Astrophysical masers can be associated with high-mass star forming regions, chief of which are methanol masers. Although this species of maser is ideal for identifying high mass star formation, it is difficult to utilise as a magnetic field tracer. Hydroxyl masers which can also be found in such regions, can crucially provide the polarimetric information, and we are currently looking at the 1720 MHz transition of hydroxyl masers coincident with positions of methanol masers from the Methanol Multibeam (MMB) survey. Primarily, we are studying the magnetic field properties of these compact sources from inherent polarization information caused by the spectral splitting of the emission lines-the Zeeman effect. This information provides us with the direction, magnetic field strength, flux of the four Stokes parameters (I,Q,U,V), position, velocity (and derived kinematic distances) with which we might be able to describe both local and large scale effects of magnetic field on the evolution of young high-mass stars within our Galaxy. We present initial results of the polarimetric properties , and derived mag- netic fields, of 1720-MHz OH masers of sources (both new and previously re- ported sources) from the MAGMO project, observed with the Australian Com- pact Array (ATCA) .

Investigating the Third Parameter in the Tully-Fisher RelationSinem OZBILGEN, University of Melbourne

One of the most important scaling relations to constrain the galaxy formation and evolution models is the Tully-Fisher Relation (TFR). The relation is between absolute magnitude and maximum rotational velocity of spiral galaxies. Our project is aiming to investigate a third parameter in the relation to achieve a tighter relation and we argue that the ratio of velocity dispersion to circular velocity could be a third parameter. It is known that the slope of the TFR changes with the morphological type, therefore, this ratio is investigated as a possible third parameter to reduce the scatter. We studied the relation with our own optical band observations of 137 early type spiral galaxies with WiFeS (Wide-Field Spectrograph) on the Australian National University (ANU) 2.3m Telescope. We then focused on to the EAGLE (Evolution and Assembly of GaLaxies and their Environments) simulation. After calculating rotational velocities and velocity dispersions of the simulated galaxy cubes, we are currently searching whether a third parameter reduces the scatter in the relation. In this talk, I will present our results from both optical observations and simulations.

Relationships between HI Gas Mass, Stellar Mass and Star Formation Rate of HICAT+WISE (HI-WISE) GalaxiesVaishali PARKASH, Monash University

I present new measurements of HI, stellar mass and star formation rate (SFR) scaling relations that exploit a combination of the Parkes HIPASS 21-cm and WISE mid-infrared surveys. Such relations are not just a natural consequence of star formation being fuelled by atomic (HI) and molecular gas (H2), but are also predicted to depend on halo angular momentum. Previous measurements from the literature show large discrepancies, often due to incompleteness. Compared to previous studies of HI galaxies, we have high completeness and obtain better stellar masses and SFRs, as WISE is far more sensitive than both 2MASS and IRAS. I will present new WISE photometry of 3,298 nearby galaxies, as it is critical for our analysis. We find that a model where HI mass is limited by halo spin parameter is consistent with the observed relationship between HI mass and stellar mass.

Gravitational Lensing of Gamma Ray BurstsJames Robert PAYNTER, The University of Melbourne

Past studies of gravitational lensing of Gamma Ray Bursts (GRBs) focused on lensing statistics to constrain the galactic population of black holes as dark matter candidates. Due to the ultra-relativistic nature of the radiating material, the emitted gamma rays are highly beamed. Thus the two different lines of sight of a lensed pair could theoretically produce two very different GRB detections. Previous studies failed to account for this subtlety, naively searching for duplicate GRBs within the data. This preliminary work focuses instead on what we can learn about GRB sources from a lensed pair, applying a much looser set of criteria to the GRB light-curves and spectrums to past data.

Understanding gas flows in and out of galaxiesStephanie Kate POINTON, Swinburne University of Technology

Simulations provide a simplistic picture of the circumgalactic medium (CGM), which suggests that low metallicity cosmic accretion occurs along the plane of the galaxy while higher metallicity gas outflows perpendicular to the disk. However, this picture has yet to be directly confirmed by observations. Independently, both the metallicity of absorption systems and the relative spatial distribution of gas around galaxies appear to be bimodal, but the spatial distribution of gas metallicities has not been explored. To address this, we use the “Multiphase Galaxy Halos” survey, which has a combination of HST imaging and UV quasar spectra as well as Keck and VLT high-resolution quasar spectra, to calculate both the metallicity and spatial distribution of absorbers associated with isolated galaxies. We have identified 53 absorbers for which we model the metallicity from hydrogen and metal lines. We present the largest study relating the metallicity to the spatial distribution of the CGM along with other physical properties of the associated galaxies. Our study provides great insight on how gas flows in and out of galaxies.

Accretion of Planetesimals within Proto-Solar Gas Rings of Non-Uniform Specific Angular MomentumAndrew PRENTICE, School of Physics & Astronomy, Monash University

It is exactly 40 years since I published a peer-reviewed description of my quantified reformulation of the Laplace nebular hypothesis for the formation of the Solar system (Prentice  1978, Moon Planets, 19, 341). According to this ‘Modern Laplacian Theory’, our planetary system condensed from a concentric family of orbiting gas rings. These gas rings were shed from the equator of the protosolar cloud (PSC) as a means for the cloud to rid excess spin angular momentum during gravitational contraction. Each ring has a nearly uniform specific orbital angular momentum h = w times s**2 and circular contours of constant density in the meridional planes that contains the axis Oz of the PSC. Here w denotes orbital angular velocity and s is cylindrical distance from the rotational axis of the PSC. The gas density in the ring declines in a Gaussian-like manner with meridional distance ‘d’ off the mean orbit {s = R, z = 0} according as exp(-A[d/R]**2). Here R is the mean cylindrical radius, where w matches the local Keplerian value and A ~ 400 is a constant. One natural advantage of the gas ring configuration is that as soon as chemical condensation into solid grains takes place, the grains migrate ‘spoke-wise’ onto the mean orbit R to form a single concentrated circular stream. That is, the gas rings focus the migrating grains onto a single Keplerian orbit in the mid-plane z = 0, thus greatly assisting the later accretion of the solid condensates into larger planetesimals though mutual gravitational attraction, to form a single solid core (cf. Hourigan 1977, Proc Astron Soc Aust. 3,169).

A major difficulty with the gas ring model for planetary accretion is that Zurek & Benz (1986, ApJ 308, 123) - and later Monaghan (1995, Earth Moon & Planets 71, 73) - discovered that gas rings are dynamically unstable. They rapidly evolve to a new orbital distribution which has specific angular momentum h that varies with cylindrical orbital distance ‘s’ according as s**(-1.75). In this paper, I solve for the density distribution of the stable evolved gas rings. I find that the density profile of the evolved gas ring retains its Gaussian mass density dependence but that the minor cross-sections of the constant density contours in the meridional plane change from being circular to elliptic. The ratio of major to minor axes equals 2**0.5 : 1. The solid condensate grains still migrate down onto the central mean orbit of the gas ring, as before, but each grain now pursues a parabolic rather than straight-line path.  That is, the evolved gas rings retain the all-important orbital focussing property. The Modern Laplacian Theory of Solar system origin has thus survived another challenge!

Clustering segregation with stellar mass and luminosity at z ~ 4 - 7Yisheng QIU, The University of Melbourne

We investigate the clustering segregation with stellar mass and luminosity among Lyman-break galaxies (LBGs) in XDF and CANDLES fields at ~ z ~ 4 - 7, and compare the results with the semi-analytic model (SAM) \textsc{Meraxes}. The observed clustering segregation is larger with luminosity than with stellar, which may contradict a naive expectation that stellar mass should be more tightly correlated with halo mass than luminosity is. However, the model reproduces the observed angular correlation functions (ACFs), and suggests a similar trend. We later find that the clustering dependence on stellar mass from the model can be weakened when uncertainties in stellar mass are taken into account. The comparison between our observations and the model also provides evidence of multiple halo occupation in small scales.

MWA EoR Data AnalysisMahsa RAHIMI, University of Melbourne

MWA EoR experiment, gathering sky radio emission sourced at Epoch of Reionization(EoR), is aimed to obtain limits of cosmological power spectra over this epoch which is of the redshift range of 6-10. These results are critical for better understanding of emergence of very first structures in the universe and evolution of the global neutral fraction. While improving calibration algorithms, we aim to place a new limit on 21-cm signal power spectra at redshift of z\sim7. For the purpose of accurate analysis of this data, we need to study different aspects of data such as observation conditions and the effect of unwanted radio emissions particularly from radio galaxy “Fornax-A”, which is demonstrated in this poster. This step helps up to effectively use MWA EoR big data and extract the targeted information out of it.

The Environments Around The Brightest Galaxies During the Epoch of ReionizationKeven REN, The University of Melbourne

We typically expect the most luminous galaxies at high redshifts to reside inside massive dark matter halos of comparable number densities, and hence expect these galaxies to be clustered. Here, I assess the validity of this assumption by investigating the clustering of the brightest objects through a combination of semi-analytic modeling and Monte Carlo simulations of mock Hubble WFC3 observations. The key aspect in our modeling is the inclusion of a log-normal scatter parameter, $\Sigma$, in the galaxy luminosity versus halo mass relation, with the lower bound, $\Sigma_{\mathrm{min}}$ being set by the distribution in halo assembly times. We show that increasing values of $\Sigma$ decreases the odds of the brightest galaxies being hosted by the most massive halo, but in less massive halos that are naturally less clustered. Our modeling with $\Sigma \geq \Sigma_{\mathrm{min}}$ is consistent with current observations ($m_{AB} \sim 27$) of the environment around bright $z > 7.5$ spectroscopic objects. Deeper observations at $m_{AB} \sim 28.2-29$ would present the opportunity to constrain, $\Sigma$ which could be used as an innovative constraint for models on early galaxy formation and evolution.

Looking for possible origins of a very metal-poor Lyman limit system towards the quasar J172323+224358Frederic ROBERT, Swinburne University of Technology

Lyman limit systems (LLSs) may be promising probes of pristine or near-pristine environments, being possibly metal-free, or polluted only by the ejecta from PopIII stars. As such, they may prove an important probe of the PopIII star population at redshifts >~ 15. Such LLSs will have a very-low metallicity, 1/1000th of the solar value, and show weak metal absorption lines against a background quasar’s continuum in the near-pristine case. There are only three such LLSs consistent with this picture. Yet, whether they are actually PopIII remnants remains unclear. I will describe my search for new similar systems, and emphasize our efforts to identify good candidates using low-resolution spectra and derive physical properties such as their metallicity through photoionization modeling. With new high-resolution quasar spectra obtained with Keck-HIRES, we identified two near-pristine systems, and one with no-apparent metal lines. Their weak C and Si lines imply metallicities ~1/2600, 1/1000, and 1/10000 (upper-limit) solar respectively. I will discuss how abundance ratios might allow to distinguish between signatures of PopIII or PopII star enrichment as the origin of the metals in these systems. I will also discuss how important it is to map the galaxy environment surrounding these LLSs. If they are circumgalactic, a galaxy (or galaxies) will be found close (<∼100kpc) to the quasar line of sight at the absorber redshift; if they are intergalactic, they will be found in an under-dense region with no nearby galaxies. Integral field spectroscopy with VLT-MUSE or Keck-KCWI allows us to test these two scenarios.

Looking for cosmic-ray acceleration in the young supernov remnant RX J1713.7-3946Gavin ROWELL, The University of Adelaide

We present the latest multi-wavelength study towards the extensively studied supernova remnant (SNR) RX J1713.7-3946. The purpose of this study is to investigate the non-thermal emission produced by accelerated particles at shock fronts and more specifically, whether these particles are hadronic or leptonic in nature within our source. We attempt to gain a better understanding of the hadronic nature of our source by dividing the SNR region into 29 smaller regions and examining each of these individually. We illustrate the success of the hadronic model in each region by fitting pion-decay models to the latest, high resolution gamma-ray, X-ray and radio observations. We then follow this up with a correlation study between the gas density and gamma-ray flux to further test the hadronic scenario.

Modeling the TeV gamma-ray enission towards HESS J1826-130.Gavin ROWELL, The University of Adelaide

HESS J1826-130 is an unidentified TeV source adjacent to HESS J1825-137. The pulsar wind nebula G018.5-0.4 and the progenitor supernova remnant of HESS J1825-137 are thought to be candidates to produce the observed TeV emission of HESS J1826-130. To quantify the contribution of these two objects, we model the transport of escaping cosmic-rays and high energy electrons as they propagate into the surrounding inhomogeneous interstellar medium. We then look at morphological and spectral features in our modeled TeV gamma-ray emission that could be observed by the upcoming Cherenkov Telescope Array.

The Cherenkov Telescope Array - 2018 StatusGavin ROWELL, The University of Adelaide

The Cherenkov Telescope Array (CTA) is the next generation TeV gamma-ray observatory. It will comprise about 120 Cherenkov imaging telescopes at two sites (northern and southern hemispheres). It will bring a transformational advance in our understanding of the TeV gamma-ray sky by probing the particle acceleration and interaction in nature's extreme environments. It will also provide a new view on the potential to understand Dark Matter. This poster will update the status of CTA as it progresses towards its pre-production phase.

The Milky Way in TeV Gamma-Rays - The New Survey from H.E.S.S.Gavin ROWELL, The University of Adelaide

The High Energy Stereoscopic System (H.E.S.S) has recently revealed its updated catalogue of over 70 TeV gamma-ray sources focusing on the southern Galactic Plane. The catalogue includes three new "gamma-ray shells" that may represent a new class of gamma-ray bright supernova remnant and a gamma-ray source potentially associated with a luminous blue variable star. The large number of sources permits for the first time detailed population studies of Galactic sources in the TeV gamma-ray band. An enduring mystery however is that over half of the source still remain unidentified. This poster will outline some key results from the survey.

Visibility storage for deep spectral line surveys using uv gridsKristof ROZGONYI, International Centre for Radio Astronomy Research

Many surveys on SKA and its pathfinders will produce data-streams that go beyond the capabilities of traditional data storage and imaging techniques (generating exa-scale datasets in the case of the SKA). One of the science applications most afflicted by this bottleneck are the proposed spectral-line surveys, having observed visibility data volumes that will significantly exceed currently available long-term storage capacity, limiting imagining pipelines to single-pass processing. As a result, options for subsequently improving the final image quality, if needed, are severely constrained. In particular, deep surveys are extremely sensitive to small systematic uncertainties, low-level RFI, and faint continuum sources, that may be unnoticeable on a daily basis, but which will emerge when observations are averaged together (over time) to create the final deep cubes. To enable both the re-processing of spectral line data, as well as meet the constraints of data storage capacity, we explore the possibility of storing gridded visibilities datasets. In my presentation, I will briefly introduce the method, the possible re-processing advantages and the method’s impact on the DINGO deep HI survey on ASKAP.

Galaxies and Intergalactic Carbon at redshifts 4 to 6 with ESO/MUSEEmma RYAN-WEBER, Swinburne University of Technology

The high redshift Intergalactic medium - including its metal content - sets the initial conditions from which modern galaxies form and evolve. We present observations from ESO/MUSE on the relationship between galaxies and metals seen in absorption towards redshift 6 quasars. We find that many carbon absorbers are in close proximity (10-80 physical kpc) to faint Lyman-alpha emitters. MUSE has been critical to this discovery as these galaxies have gone undetected in HST and ground-based narrow-band imaging. The observations confirm the hypothesis that intervening metal absorbers are NOT due to stellar feedback associated with the highest density peaks at early times, but rather they are dispersed by recent star formation in low luminosity galaxies close to the quasar line of sight.

Black Hole Mass Scaling Relations In Early-Type GalaxiesNANDINI SAHU, Swinburne University of Technology, Melbourne

Our aim is to better establish the relation between the black hole mass of a galaxy and both the spheroidal stellar mass and the galaxy stellar mass. My research involving near-infrared and optical images of ~90 early-type galaxies has revealed a near quadratic relation for both. This relation can be used to estimate the black hole mass of a galaxy from photometry. Coalescence of black holes during collisional evolution of a galaxy pair is a key source of gravitational waves. Knowledge of the masses of colliding black holes from the above relation, along with the frequency of galaxy mergers, will help us constrain the rate of occurrence and the wavelength of gravitational waves actively searched for by pulsar timing arrays.

The Gateway Science: A Review of Astronomy in the School Curriculum around the OECD CountriesSaeed SALIMPOUR, Deakin University/Edith Cowan University

Astronomy and its cognate fields, encompassed by space sciences, have been considered a gateway science, owing to its gravitas to pique the curiosity of everyone irrespective of age, culture or inclination to science. The inclusion of astronomy in the school curriculum has waxed and waned over the years. In the current era, there is a global push to get more students engaged in Science, Technology, Engineering and Mathematics (STEM), ergo, astronomy provides an invaluable conduit to bring about this shift. This paper highlights the results of a study which has reviewed the presence and extent to which astronomy has been incorporated into the school curriculum of the Organisation for Economic and Cooperative Development (OECD) member countries as well as two non-OECD countries strong in astronomy research, China and South Africa and one international curriculum, the International Baccaleureate Diploma programme. A total of 52 national curricula from 37 countries were reviewed, the results revealed that overall astronomy and its cognate topics are prevalent in at least one grade in all curricula across the OECD, China and South Africa. Of the 52 national curricula, 44 of them had astronomy related topics in grade 6. Out of the 52 national curricula, 40 introduced astronomy-related topics in grade 1, while 14 of them had astronomy-related topics explicitly mentioned in all grades. The most common keywords were related to basic astronomy concepts, all have occurrences of over 100. Relational textual analysis also revealed that all the major concepts could be encompassed across two broad themes of Earth and Physics.

The Parkes Testbed Facility DevelopmentJohn SARKISSIAN, CSIRO Astronomy and Space Science, Parkes Observatory

The 12m antenna of the Parkes Testbed Facility (PTF) was commissioned in 2009 as a test platform for CSIRO’s program of developing PAF receiver technology. The system was recently used to monitor the Vela pulsar for timing glitches, resulting in a glitch detection on 12 December 2016. The current Mark-I PAF has severe limitations owing to the vagaries of the PAF backends. Consequently, the PTF is being developed to expand its capabilities. The plan is to install an ASKAP L-band feed that will allow the monitoring of pulsars to be performed more efficiently, since a continuous data stream and lower system temperatures could be provided. Also, by using the soon-to-be decommissioned DFB4 correlator of the Parkes 64m telescope, an existing pulsar backend can be used with little or no modification required. Other possibilities include fitting the PTF with a wideband feed and even installing a prototype, cryogenically cooled PAF to complement the one planned for the 64m telescope. Finally, the wide field of view and high availability of the PTF, presents opportunities for detecting FRB’s. Plans are also being developed, to use the PTF as a learning/teaching instrument, both to train new observers and engineers and to test new techniques.

SAMI Galaxy Survey Data Release 2: Absorption-line PhysicsNic SCOTT, The University of Sydney

We present the second data release from the Sydney-AAO Multi-bundle Integral field Spectrograph (SAMI) Galaxy Survey at the Anglo-Australian Telescope. The data release will contain reduced spectral cubes for 1559 galaxies at 0.02 < z < 0.10. This release will also include stellar kinematic and stellar population value-added products derived from absorption line measurements, and all emission line value-added products from Data Release One. Our poster will highlight several galaxies from the SAMI Galaxy Survey that have interesting stellar and gas kinematics. For more information about data release 2, please see: https://sami-survey.org/abdr

Westerlund 1 - One of the Milky Way's extreme accelerators?Cameron SNOSWELL, University of Adelaide

Westerlund 1 is one of our galaxy's extreme stellar clusters, harbouring over 20 Wolf-Rayet stars, a magnetar, XX O-tpye stars and XX yellow supergiants. Westerlund 1 is at the centre of the largest TeV gamma-ray source (2 deg. diameter) in the southern Galactic plane. In order to better understand the type of particles responsible for this gamma-ray emission, and where they may be coming from, we have studied the molecular gas using the Mopra telescope focusing on the CO and CS molecular tracers. Here we present our preliminary results obtained so far.

The DREAMS of Siding Spring ObservatoryJamie SOON, Australian National University

The Dynamic REd All-sky Monitoring Survey (DREAMS) is a wide-field near infrared Y, J, and H band survey designed to take advantage of a combination of off the shelf and custom designed components in order to maximise return for the scientific goals. DREAMS will have an unprecedented survey speed to explore the infrared sky and provide connections to other all-sky surveys as well as providing targets for follow-up searches. DREAMS will deliver a distinct advantage for transient detection and observing regions with high optical extinction. DREAMS will be carried out on a 0.5m aperture fully automated telescope scheduled to begin construction in 2018. We present an overview of DREAMS along with the current status and development of the telescope including the optical telescope assembly, mechanical design, and infrared detector.

Detecting gravitational-wave memory with LIGOColm TALBOT, Monash University

The gravitational-wave memory effect is a fundamental prediction of general relativity, which states that the emission of gravitational waves leads to a permanent deformation of space, which persists after the oscillatory signal. Measuring the memory effect will require waveforms which can be used in Bayesian inference codes. However, it is difficult to extract the memory waveform from numerical relativity simulations. In this talk, I describe new tools for the fast calculation of memory waveforms from arbitrary oscillatory signals. I use the new tool to explore the geometric features of memory from binary black hole mergers.

Progress on the optimal search for an astrophysical gravitational-wave backgroundEric THRANE, Monash University

Roughly every 2-10 minutes, a pair of stellar mass black holes merge somewhere in the Universe. A small fraction of these mergers are detected as individually resolvable gravitational-wave events by advanced detectors such as LIGO and Virgo. The rest contribute to a stochastic background, which encodes valuable information about the mass and distance distribution of black holes throughout the Universe. In this talk, I describe the recently derived optimal search method for a background of binary black holes. The optimal method applies Bayesian parameter estimation in order to leverage our knowledge of merger waveforms, leading to a >1000-fold reduction in the expected time to detection. I describe progress on a mock data challenge designed to demonstrate the algorithm under realistic conditions.

X-ray Ionised Nebulae in Nearby GalaxiesErica Aileen THYGESEN, Curtin University

Star-forming regions in galaxies produce intense ultraviolet flux that can influence their local environments. Some star-forming regions also include Helium III regions, which are volumes of interstellar gas that show signs of emission from doubly-ionised helium. He III regions require large amounts of high-energy photons to ionise the helium nebula. Usually the highest energy ultraviolet photons from star-forming regions are emitted from Wolf-Rayet stars, which are hot enough to doubly ionise helium. However, a study led by Shirazi and Brinchmann (2012) found a population of star-forming galaxies containing He III regions that may not exhibit Wolf-Rayet features, such that the source of ionising photons remains a mystery. It is possible that another ionising source is present in these galaxies – perhaps in the form of an accreting compact object. I will present a subset of 16 galaxies from Shirazi & Brinchmann (2012) that have archival X-ray observations taken by Chandra to determine if accretion powered ultraviolet and X-ray emission are the source of ionising photons in these galaxies. I will discuss implications of our results in regards to the demographics of black holes and neutron stars in star-forming regions, and the impact that accreting compact objects could have in ionising their nearby environments in both the local and high-redshift Universe.

Studying Low Frequency Pulsar Polarimetry with the MWASteven TREMBLAY, CIRA

Studying the polarimetric properties of pulsars is a critical part of understanding the configuration of magnetic field lines within any given pulsar’s magnetosphere. Performing this with low frequency data allows us to investigate the emission physics at higher altitudes above the star’s surface, while also sampling a larger fraction of the magnetosphere. These data also allow us unparalleled leverage for measuring the Faraday rotation caused by the intervening interstellar medium due to its strong dependence upon wavelength. I will present the polarimetric work being performed on select pulsars with the MWA, along with the current status of our two-pronged polarimetric calibration verification.

Inferring the population properties of binary neutron stars with gravitational-wave measurements of spinXingjiang ZHU, Monash University

The recent LIGO-Virgo detection of gravitational waves from a binary neutron star inspiral event GW170817 and the discovery of its accompanying electromagnetic signals mark a new era for multi-messenger astronomy. In the coming years, advanced gravitational-wave detectors are likely to detect tens to hundreds of similar events. Neutron stars in binaries can possess significant spin, which is imprinted on the gravitational waveform via the effective spin parameter . We explore the astrophysical inferences made possible by gravitational-wave measurements of spins . First, based on radio pulsar observations, we estimate that 15-30% of binary neutron stars should have spins measurable at the 90% confidence level by advanced detectors. Second, using Bayesian inference, we show that it is possible to tell whether or not the spin axis of the recycled neutron star tends to be aligned with the binary orbit after 30 detections. Finally, interesting constraints can be placed on neutron star magnetic field decay after 300 detections.

Untangling the dense and disrupted gas towards HESS J1745-303Phoebe DE WILT, University of Adelaide

HESS J1745-303 is an extended, very high energy gamma-ray source discovered in the first H.E.S.S. Galactic Plane Survey. The overlapping supernova remnant (SNR) G359.1-0.5 interacts with an adjacent molecular cloud as evidenced by a cluster of 1720 MHz OH masers towards the SNR rim. 3 to 7mm observations with Mopra have identified molecular gas counterparts towards all regions of TeV emission, of which broad line components trace the molecular cloud previously attributed to the TeV emission in region A and narrow line components of gas towards all regions of TeV emission at the velocity of the 1720MHz OH masers.

“ATESE” project: past, present and future researchnoor masdiana MD SAID, University of Tasmania

Over the last few years, “ATESE” project is actively involved in discovering the extreme scattering events (ESEs). This project has resulted in identification of new intra-day (IDV) and intra-hour (IHV) variables. Most recently, we have discovered that extreme scattering events arises in the vicinity of local, hot stars. An overview of project developments and future plans are presented.

Three-Dimensional Vectors of High Velocity Cloudskarlie NOON, Australian National University

The Milky Way experiences a constant source of gas inflow and outflow onto and from its disk. Inflow of gas is required in order to support the Galaxy’s observed star formation rate and outflow is the result of winds and supernovae processes within the disk. Evidence of these two processes are seen through small clouds of atomic gas with abnormal velocities, floating around the Galaxy. The net flow of these high velocity clouds (HVC) is mostly unknown. Distance and trajectories are essential for answering this question. However, there are very few techniques for measuring either of these. Heitsch et al (2016) proposed a method to estimate the full three-dimensional velocity vector and distance of a compact HVC from the cloud’s morphology. As a test, we have applied this method to the well-known Smith Cloud, which is one of the few HVCs with an independent estimate of its velocity vector and distance, and found consistent results. We have now extended the method using an improved rotation model for the Milky Way and have applied it to a larger sample of HVCs, for which we provide distances limits and trajectories.

Rapid analyzing of models with PRISMGerrit Willem VAN DER VELDEN, Centre for Astrophysics and Supercomputing, Swinburne University of Technology

Typically we probe the universe by making models that try to reconstruct reality based on our scientific knowledge. Since our knowledge is limited, models tend to only tell part of the story. Commonly we utilize MCMC methods in order to check how closely this resembles reality. MCMC however has a few drawbacks: It is slow, requires much additional knowledge about the model and is vulnerable to irregularities. To address this, I am developing a tool that solves this problem by approximating the model with an emulator, called PRISM. In this talk, I will introduce PRISM and discuss its future plans, applications and contributions. I will also show early results of using one of the latest state-of-the-art Semi-Analytic Models, the Meraxes model.