Navigation News Annual Scientific Meeting Participants Program Posters Events Opening Reception ESO Agreement Signing Harley Wood Public Lecture ASA Conference Dinner Introduction To Machine Learning Prizes Bok Prize Charlene Heisler Prize Ellery Lectureship Harley Wood Lecture Louise Webster Prize Policies Sponsors Harley Wood Winter School
News Annual Scientific Meeting News Participants Program Posters Events Opening Reception ESO Agreement Signing Harley Wood Public Lecture ASA Conference Dinner Introduction To Machine Learning Prizes Bok Prize Charlene Heisler Prize Ellery Lectureship Harley Wood Lecture Louise Webster Prize Policies Sponsors Harley Wood Winter School

Astronomical Society of Australia's Annual Scientific Meeting – Program

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

If you'd like to download a copy of the program, you may do so from here (412.8 KB).

Sun, 9 Jul | Mon, 10 Jul | Tue, 11 Jul | Wed, 12 Jul | Thu, 13 Jul | Fri, 14 Jul

Sun, 9 Jul

4:00–7:00 p.m.

Sun, 9 Jul, 4:00 p.m. to 7:00 p.m. Day ↑ | Top ↑


University House

Registration will open at 4pm, and will remain open until the end of the Opening Reception.

Opening Reception

Registration required

4:30 p.m. – 6:30 p.m. @ University House, ANU

This event is sponsored by the ANU Research School of Physics and Engineering.

The Opening Reception for the Annual Scientific Meeting will take place at ANU University House on Sunday, 9 July. Drinks and canapés will be provided.

The registration cost for this event is free for those attending the ...

More info →

Mon, 10 Jul

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

Mon, 10 Jul, 9:00 a.m. to 9:15 a.m. Day ↑ | Top ↑

Welcome to Country

Molonglo Theatre

A Welcome to Country Ceremony will be conducted by Ngunnawal Elder Tyronne Bell.

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


Molonglo Theatre

A welcome address will be made by Professor Brian Schmidt AC, Vice-Chancellor of The Australian National University.

Mon, 10 Jul, 9:30 a.m. to 10:30 a.m. Day ↑ | Top ↑

Session 1 – Results from the Murchison Wide-Field Array

Molonglo Theatre

T1, 9:30–9:45 a.m. — Murchison Widefield Array: Science and technology on the path to SKA
Randall WAYTH, Curtin University

The Murchison Widefield Array (MWA) radio telescope is the technical and scientific precursor instrument to the Low Frequency component of the future Square Kilometre Array (SKA-Low). It was built by an international science collaboration from six countries and is located in the remote Murchison region of Western Australia. Scientifically, the MWA has generated results on the Earth's ionosphere, the heliosphere, nearby stars, our Galaxy, distant galaxies and AGN, and all the way back to the early universe. The MWA has been in full operations since mid 2013 and the expertise gained in designing and operating a low frequency radio telescope has had direct benefits to SKA-Low in the pre-construction phase. This talk will provide an overview of the status, science and technical progress of the MWA, including the SKA context.

T2, 9:45–10:00 a.m. — Fireballs, the ionosphere, and space debris from the MWA
Paul HANCOCK, Curtin University

The MWA has been engaged in a number of projects that focus on observing the very local universe. Events, objects, and propagation effects in the last nano-parsec can form an important foreground which must be considered by projects interested in the more distant universe. In this talk I'll describe the effects of the ionosphere, the incidence and influence of Fireballs, and our ability to detect space debris with the MWA.

T3, 10:00–10:15 a.m. — A multi-frequency radio continuum study of the Magellanic Clouds
Bi-Qing FOR, International Centre for Radio Astronomy Research/University of Western Australia

The GaLactic Extragalactic All-Sky MWA (GLEAM) survey is the main MWA continuum survey that covers the sky south of declination +30 degrees and at frequencies between 72 and 231 MHz. We utilize the data from the GLEAM survey to carry out a continuum study of the Magellanic Clouds. I will present the derived global spectral indices and radio spectral index maps. In conjunction with multiwavelength data, we investigate the star formation rate and discuss the implication of varying spectral index across the Magellanic Clouds in relation to star formation processes.

T4, 10:15–10:30 a.m. — Engineering Development Array: A low frequency radio telescope utilising SKA precursor technology
Marcin SOKOLOWSKI, Curtin University

We present the design and performance of the Engineering Development Array (EDA), which is a low frequency radio telescope comprising 256 dual-polarisation dipole antennas working as a phased-array. The EDA was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array (SKA) precursor technology and expertise, specifically from the Murchison Widefield Array (MWA) radio telescope. It demonstrates the practicality and feasibility of using MWA-style precursor technology for SKA-scale stations. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the EDA's receiver temperature as a function of frequency and shown that the EDA is sky-noise dominated over most of the frequency range measured between 60 and 240 MHz. We used the EDA in interferometric mode with the MWA in order to derive absolute sensitivity of the array from calibrated visibilities. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature.

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

Morning Tea

Foyer, Crawford School of Public Policy

Mon, 10 Jul, 11:00 a.m. to 12:30 p.m. Day ↑ | Top ↑

Session 2 – Results from SkyMapper

Molonglo Theatre

T5, 11:00–11:15 a.m. — The First Data Release of SkyMapper's Southern Sky Survey
Christopher ONKEN, The Australian National University

We present the first Data Release from the SkyMapper telescope's Southern Sky Survey. DR1 covers approximately 20,000 square degrees to a depth of ~18mag in the 6 standard SkyMapper filters (uvgriz), and includes photometry for roughly 300 million stars and galaxies. Proprietary access to the survey products is being provided to Australian astronomers through the All-Sky Virtual Observatory, and we will describe the tools available for catalogue queries, image cutouts, and cross-matching to other datasets.

T6, 11:15–11:15 a.m. — The SkyMapper Search for Extremely Metal-Poor Stars in the Galactic Halo
Gary DA COSTA, Australian National University

The filter system employed in the SkyMapper survey of the southern sky incorporates a narrow ‘v’ filter centered on the Ca II K-line at 3933Ang, facilitating the identification of extremely metal-poor (EMP) stars in the photometric dataset. A initial survey carried out during telescope commissioning resulted in the discovery of the most iron-poor star known (SMSS J0313-6708) and a further 41 stars with [Fe/H] < -3.0 dex in the Galactic halo. In this contribution we present initial results from a new search for Galactic halo EMP stars based on SkyMapper Survey data. We will discuss the selection process, possible biases, outcomes from the on-going low resolution spectroscopic follow-up program with the ANU 2.3m telescope at Siding Spring Observatory, and initial results from high-dispersion follow-up observations of promising candidates.

T7, 11:30–11:45 a.m. — An atlas of SFR changes in nearby galaxies from SkyMapper
Christian WOLF, The Australian National University

The SkyMapper filter set with its special violet 'v' filter probes the A star contribution in the integrated light of stellar populations at low redshift of z<0.03, relative to both younger and older stars. SkyMapper photometry thus shows whether the star formation rate in a galaxy has recently changed. The diagnostic is similar to H-delta absorption line measurements in IFUs, and its signal peaks 150 Myr after a change in star-formation rate. SkyMapper will provide a galaxy atlas, where local SFR changes are mapped with sub-kpc resolution. The diagnostic works in all NGC/IC galaxies as well as the Fornax and Virgo South Clusters.

T8, 11:45 a.m. –12:00 p.m. — The SkyMapper High-Redshift Quasar Survey
Fuyan BIAN, Australian National University

The luminous quasars at z>5 directly probe the early growth of supermassive black holes and the relation between the formation of early galaxies and black holes. The SkyMapper Southern Survey will cover the whole Southern hemisphere in six optical bands. In this talk, I will highlight one application of the deep Main Survey component, the search for quasars at redshift z>5, and show first results from the released Short Survey data and experimental Main Survey data. We plan to discover bright high-redshift quasars and create a complete sample with massive ancillary-science spectroscopy in Taipan, with the long-term aim of measuring the growth in the black-hole mass function between 750 and 1500 million years after the Big Bang.

T9, 12:00–12:15 p.m. — Update on the SkyMapper Transient Survey: type Ia supernovae and other transients
Anais MÖLLER, Australian National University

The SkyMapper Transient (SMT) survey is performing a rolling search of the southern and equatorial sky utilizing the SkyMapper Telescope at Siding Spring Observatory. Its main goal is to obtain an untargeted sample of type Ia supernovae (SNe Ia) for cosmology. SkyMapper aims to have $>100$, well calibrated, low redshift ($z<0.1$) type Ia supernovae. In addition, the SkyMapper Transient survey aims to discover interesting transients and counterparts for gravitational waves and fast radio burst events. In this talk we will give an update of the SMT survey with a particular focus on supernovae. To date SkyMapper has discovered over 40 spectroscopically confirmed supernovae including 31 Type Ia, SNIa 2016hhd discovered within the first few days of explosion with possible evidence of a shock interaction and, peculiar Type IIn SN 2015J with a triple-peaked light curve. We have participated in the search for optical counterparts of gravitational waves as well as fast radio bursts and other transients including a collaboration with the Deeper, Wider, Faster program. The SkyMapper Transient Survey is in full operation and discovering a large number of transients. The SkyMapper supernovae data set will be valuable as a search and follow-up survey uniformly observed and reduced, and non-targeted sample of low-redshift SNe Ia.

T10, 12:15–12:30 p.m. — A First SkyMapper Variability Census and the Search for Counterparts to High-energy Events
Seo-Won CHANG, The Australian National University

SkyMapper searches for optical counterparts of high-energy events such as fast radio bursts and sources of gravitational waves. The latter involves follow-up observations of more than 100 sq. deg. per event. A large field of view is crucial to deal with the current uncertainties in localisation, but there will be many variable sources contaminating the counterpart candidate list. Here, we present a variability census of the SkyMapper Data Release 1 (DR1) to better understand characteristic timescales and amplitudes of potential contaminants. Several metrics are used to characterize large-amplitude variable sources whose signal can mimic that of a counterpart. We examine the effects of survey depth and cadence of visits for the constraints on the type of variable. We also discuss the variability metrics that we apply to our multi-band, time-series data and provide substantial new data for previously known variables.

Mon, 10 Jul, 12:30 p.m. to 2:30 p.m. Day ↑ | Top ↑


Foyer, Crawford School of Public Policy

The Future of Optical Astronomy in Australia – Sponsored by AAO

Molonglo Theatre

This session will be a discussion of the opportunities provided by Australian membership of ESO, and the ongoing arrangements for AAT operations and the AAO Instrumentation program.

All are welcome.

Mon, 10 Jul, 2:30 p.m. to 4:15 p.m. Day ↑ | Top ↑

Session 3 – Instruments and Facilities

Molonglo Theatre

T11, 2:30–2:45 p.m. — Opening the dynamic infrared sky with DREAMS
Anna MOORE, Australian National University

While optical and radio transient surveys have enjoyed a renaissance over the past decade, thedynamic infrared sky remains virtually unexplored. The infrared is a powerful tool for probing transient events in dusty regions that have high optical extinction, and for detecting the coolest of stars that are bright only at these wavelengths. The fundamental roadblocks in studying the infrared time-domain have been the overwhelmingly bright sky background (250 times brighter than optical) and the narrow field-of-view of infrared cameras (largest is VISTA at 0.6 sq deg). To address this challenge, we propose a low risk, economical and agile instrument located in an existing housing at Siding Spring Observatory. The proposed Dynamic REd All-sky Monitoring Survey (DREAMS) has the ability to observe the southern hemisphere sky every 25 hours at infrared wavelengths with transient sources released routinely to the community beginning late 2018.

T13, 2:45–3:00 p.m. — The Huntsman observing systems: the frontier of extremely low surface brightness observations
Lee SPITLER, Macquarie University & Australian Astronomical Observatory

Extremely faint, extended structures in the universe contain rich information about astrophysical processes. At the outer edges of galaxies, stellar streams and the halo contain a record of billion years of mass assembly. The cosmic infrared background captures a view of the integrated history of the universe. Sunlight scattered off the dust in our Solar System provides clues about the evolution of planetary systems. And the extended faint envelope of evolved stars provides insight on the chemical pollution of the interstellar medium. In this talk I will describe two facilities designed to access these faint observational targets for the first time. The Huntsman Telephoto Array is an array of off-the-shelf Canon lenses based at Siding Spring Observatory that can explore uncharted low surface brightness regions around galaxies and stars. The Australian Space Eye (‘Huntsman in Space’) is a miniature space telescope concept to monitor the zodiacal light and directly measure the cosmic infrared background.

T17, 3:15–3:30 p.m. — CACAO: A Cheap And Compact Adaptive Optics system
Jamie SOON, Australian National University

Adaptive Optics (AO) corrects for the blurring of images caused by disturbances in the transmission medium. AO is normally thought of as related to correcting for the Earth's atmosphere when capturing astronomical images but it can also be used to correct for aberrations in different systems which occur via other transmission mediums; for example in retinal imaging, horizontal beam propagation, or laser beam cleaning in laboratory applications. The main component of an AO system is the deformable mirror which determines the system cost, specifications, properties and corrective abilities. A Cheap And Compact Adaptive Optics (CACAO) system is currently under development at the ANU which is built around a relatively inexpensive deformable mirror, that has 40 actuators combined with additional tip-tilt capability. This will involve evaluating and characterising the deformable mirror to determine its performance, limitations and potential. The development of CACAO will include testing to determine its capabilities as part of an astronomical AO system and whether the deformable mirror is capable of achieving correction on a telescope in the 1-2m diameter range. Testing will also be undertaken for a range of other scenarios in order to determine the capabilities and other possible applications for the deformable mirror; these different scenarios will include biomedical applications and laser beam cleaning.

T18, 3:30–3:45 p.m. — LSST and Australia
Sarah BROUGH, University of New South Wales

Australian astronomers have access to the Large Synoptic Survey Telescope (LSST) through agreements made by CAASTRO+AAO as well as ICRAR. This is an 8.4m optical survey telescope under construction in Chile. It will survey the Southern Sky to unprecedented depths over a 10-year multi-epoch campaign. I will introduce LSST and the groundbreaking science this survey telescope will undertake and outline ways Australian astronomers can get more involved.

T20, 3:45–4:00 p.m. — Maunakea melting pot: Opportunities for Australia with EAO
Jessica DEMPSEY, East Asian Observatory

The East Asian Observatory has been operating the JCMT on Maunakea for two years. With a focus on international scientific collaboration and the career enhancement of young astronomers, EAO now looks to deepen its portfolio, with an ambitious instrument program for JCMT, as well as new partnerships with leading facilities such as Subaru. Within the changing political and scientific landscape on Maunakea, synergy between Observatories and international collaboration are more critical than ever before. Opportunities for Australia and East Asian regional partnership in instrumentation, science and observatory management will be presented. 

Session 4 – Results from ASKAP

Barton Theatre

T12, 2:30–2:50 p.m. — HI accretion, the Cosmic Web and WALLABY early science
Dane KLEINER, CSIRO Astronomy and Space Science

We examine the HI-to-stellar mass ratio (HI fraction) for galaxies in filaments within the nearby Universe (d < 181 Mpc). HI stacking of HIPASS spectra and 6dFGS stellar mass estimates yield the HI fraction for filament galaxies at different stellar masses and projected densities. In an attempt to disentangle what influences cold gas in galaxies, we find galaxies with high stellar masses have a systematically higher HI fraction near filaments than the control sample (Kleiner et al. 2017). I will present the data and discuss evidence for massive galaxies accreting cold gas from the intergalactic medium which can replenish some HI gas. Furthermore I will give an update on the progress of WALLABY Early Science, incl. preliminary results on the nearby spiral galaxy IC 5201 and its environment as revealed after combining multi-epoch ASKAP-12 observations.

T14, 2:50–3:10 p.m. — Scientific validation of ASKAP continuum data
Jordan COLLIER, CSIRO Astronomy and Space Science / Western Sydney University

The Australian Square Kilometre Array Pathfinder (ASKAP) is currently undergoing commissioning, and is continuing to put out high-quality data products. The Evolutionary Map of the Universe (EMU) survey will use ASKAP to produce a deep (~10 uJy rms) radio continuum map of the whole Southern Sky, containing ~70 million radio sources, as compared to the 2.5 million radio sources currently known. EMU Early-Science is well underway, and several key fields have been observed with ASKAP. As part of commissioning, these data need to be validated for science, both for commissioning the instrument and assessing its performance, and for beginning to develop the framework for the automated quality control and scientific verification that will be necessary for EMU. I will discuss the automated pipeline I have developed to produce a science validation report of ASKAP continuum data, the current results and the next steps.

T16, 3:10–3:30 p.m. — The cold gas reservoir feeding an adolescent radio galaxy
James ALLISON, University of Sydney / ASTRO-3D

While some radio galaxies show stong emission lines in the optical, characteristic of an active galactic nucleus, others do not. We have substantial circumstantial evidence that this dichotomy is the result of the mode in which gas is accreted onto the nucleus. However, the exact mechanisms by which high and low excitation radio galaxies are nourished can only be determined through direct observation of the gas. A powerful method for measuring the kinematics of gas deep into the centres of radio-loud AGN is through detection of the HI 21-cm hyperfine and CO rotational lines in absorption. ASKAP, in its commissioning and early science phase, has been very successful in detecting HI absorption in radio galaxies at intermediate cosmological redshifts. In followup observations using ALMA we have detected CO(2-1) absorption in PKSB1740-517, a young powerful radio galaxy at z=0.5. I will discuss the results of this work, including how we can disentangle the line-of-sight ambiguities from absorption and what we learn about the system by combining the ASKAP, ALMA and multiwavelength ancillary data.

T19, 3:30–3:50 p.m. — The discovery of a population of bright fast radio bursts with the Australia Square Kilometre Array Pathfinder

Fast radio bursts (FRBs) remain one of the most exciting and confounding classes of astronomical transients. There is mounting evidence that these bright, dispersed pulses of radio emission originate at cosmological (Gigaparsec) distances. Not only do the energetics of the events point to a new radiative process, but the pulses are imprinted with propagation through the ionised intergalactic medium and cosmic web, making them invaluable probes of media invisible to most other types of observations. Despite considerable effort to detect additional bursts, the yields have been low because of relatively narrow fields of view of most searches. Here I will present the discovery this population from a wide-area survey conducted with the Australia Square Kilometre Array Pathfinder (ASKAP), which leveraged the telescope’s phased-array feeds (PAFs) and utilized a fly’s eye search strategy. I will highlight the discoveries to date, which have yielded three FRBs in ten days of searching, as of the abstract submission, and likely more between then and the conference. I will additionally show how we can use the PAF detections to better localize and measure the fluences of the bursts than other larger telescopes. I conclude by presenting future plans to develop interferometric fast transient capabilities with ASKAP, necessary to harness the full value of FRBs.

Afternoon Tea

Foyer, Crawford School of Public Policy

Mon, 10 Jul, 4:15 p.m. to 5:15 p.m. Day ↑ | Top ↑

Session 5 – Planet Formation

Molonglo Theatre

T21, 4:15–4:30 p.m. — Constraints on the radial extent of debris disks from unresolved continuum emission

Debris disks – tenuous rings of icy and rocky material produced by the breakup of asteroids and/or comets around main sequence stars – are inferred to denote the presence of a planetary system. These disks are most commonly detected through the measurement of excess emission at infrared wavelengths from the host star. In most cases, the emission is spatially unresolved, so the radial extent of the disk is not precisely known. Far-infrared observations of a sample of well-studied, spatially resolved debris disks have revealed a simple relationship between stellar luminosity and disk extent. This scaling can be applied to unresolved debris disks, that comprise the vast bulk of known systems.. Remnant debris marks the outer edge of a planetary system, so we would expected to find planetary companions to the host star interior to the debris disk. Accurate determination of the extent of a large group of planetary systems therefore provides a first glimpse into the range of radial separations at which planet formation may occur. Self-stirring models of disk evolution predict a characteristic outward migration of the disk over time, whereas planetary migration may drive the disk outward more quickly. Comparison of the disk extent derived from observation with self-stirring models will identify those that are anomalously large for their age and therefore may be undergoing a disk-planet interaction. Here I present an analysis of archival Spitzer and Herschel far-infrared observations, both resolved and unresolved, to identify those that are potentially in a phase of disk-planet interaction through migration. I also present a comparison of the stellar luminosity-disk radius relationship derived at far-infrared wavelengths with that based on disk observations at sub-millimetre wavelengths.

T23, 4:30–4:45 p.m. — The effect of non-ideal MHD on disc winds from protoplanetary discs
James TOCKNELL, Macquarie University

Magnetically-driven disc winds have significant effects on the evolution of protoplanetary discs, via the removal of angular momentum and mass from the disc. However, existing models typically ignore non-ideal magnetohydrodynamic effects, such as Hall drift, but these are known to operate inside these discs, and affect their structure and evolution, for example suppressing magnetically-driven turbulence and magneto-rotational instability. In light of this, I will present preliminary results of self-similar disc wind models which include non-ideal magnetohydrodynamic effects within the disc.

T25, 4:45–5:00 p.m. — Tiny grains shining bright in the gaps of Herbig Ae transition discs
Eloise BIRCHALL, Australian National University

Protoplanetary discs exhibit structures such as rings, gaps, asymmetries, and spiral arms, which can be interpreted as signs of planet formation. Around Herbig Ae stars such as Oph IRS 48 and HD 169142, these structures are prevalent in the outer disc regions. In this work, we examine the regions inward of approximately 20AU, where these discs are thought to be mostly cleared of material. We find that there are disc structures and features in these inner regions that are bright in the near-infrared. The inner disc structures are made up of very small dust grains, and in some cases these inner structures could be misinterpreted as planets.

T27, 5:00–5:15 p.m. — Binary Star Formation and the Outflows from their Discs
Rajika KURUWITA, Australian National University

We carry out magnetohydrodynamical simulations with FLASH of the formation of a single, a tight binary (a ~2.5AU) and a wide binary star (a ~ 45AU). We study the outflows and jets from these systems to understand the contributions the circumstellar and circumbinary discs have on the efficiency and morphology of the outflow. In the single star and tight binary case we obtain a single pair of jets launched from the system, while in the wide binary case two pairs of jets are observed. This implies that in the tight binary case the contribution of the circumbinary disc on the outflow is greater than that in the wide binary case. We also fi nd that the single star case is the most efficient at transporting mass, linear and angular momentum from the system, while the wide binary case is an order of magnitude less efficient. The tight binary's efficiency falls between the other two cases, but converges towards the single star case when considering the angular momentum transport. By studying the magnetic field structure we deduce that the outflows in the single star and tight binary star case are magnetocentrifugally driven, whereas in the wide binary star case the outflows are driven by a magnetic pressure gradient.

Session 6 – High-Energy/Particle Physics

Barton Theatre

T22, 4:15–4:30 p.m. — Low luminosity thermonuclear supernovae as the origin of most Galactic antimatter

Our Galaxy hosts the annihilation of a few ×10^43 positrons every second. Radionuclides capable of supplying such positrons are synthesised in stars, stellar remnants, and supernovae. For decades, however, there has been no positive identification of a main stellar positron source. This has led to suggestions that many positrons originate from exotic sources like the Galaxy’s central super-massive black hole or dark matter annihilation, but such sources would not explain the recently-detected positron signal from the extended Galactic disk. We show that a single type of transient source, deriving from stellar populations of age 3-6 Gyr and yielding ∼ 0.03 M⊙ of the positron emitter 44Ti, can simultaneously explain the absolute positron luminosity of the Galaxy and the morphology of the annihilation signal. Our binary population synthesis modelling demonstrates that this transient is likely the merger of two low-mass white dwarfs, likely observed in external galaxies as a particular sub-luminous, thermonuclear supernova, known as SN1991bg-like. [This work has recently been accepted for publication in Nature Astronomy]

T24, 4:30–4:45 p.m. — Recent Anisotropy Studies With The Pierre Auger Cosmic Ray Observatory
Roger CLAY, University of Adelaide

The Pierre Auger Observatory is the world’s largest cosmic ray observatory. It has been in full operation for almost a decade, giving it the largest ever exposure at ultra-high energies. The Auger dataset at those highest energies is large enough to enable astrophysically significant studies to be made of both broad-scale and hot-spot anisotropies in the southern sky. Through the selection of particular classes of events, searches can also be made for point sources associated with uncharged messengers. Recent Auger anisotropy data will be presented together with discussion of their possible astrophysical interpretation.

T26, 4:45–5:00 p.m. — Detecting high-energy cosmic particles with radio telescopes
Clancy William JAMES, Curtin University

The 'radio-particle' technique allows radio telescopes to study the highest-energy cosmic rays and neutrinos. When these particles interact in a medium, they produce a nanosecond burst of emission that can be detected in the MHz-GHz regime. Advances in both digital signal processing technology and the theory of the emission have led to a recent surge in experimental activity using this technique. In particular, it has allowed LOFAR to make the most precise measurements of cosmic ray composition near 10^17 eV, and Parkes and others to limit the flux of extremely energetic neutrinos. After briefly reviewing the status of the field, possibilities for groundbreaking observations of cosmic rays in the Earth's atmosphere and on the Moon with the MWA, ASKAP, and Parkes will be described. Finally, the technique is now the focus of the Square Kilometre Array's High Energy Particle Focus Group, and I will outline plans to detect an unprecedented number of ultra-high-energy cosmic rays, and study extensive air showers with ultimate precision.

T28, 5:00–5:15 p.m. — A quantum of darkness: making particles invisible
Allan ERNEST, Charles Sturt University

Understanding the nature and origin of dark matter remains one of the greatest challenges facing modern astronomy and cosmology. The leading theoretical paradigm, Lambda Cold Dark Matter (LCDM), works well on the largest scales but encounters significant issues on the cluster scale and below, and additionally requires the existence of an as-yet-undiscovered particle. Quantum theory however, could solve the dark matter problem entirely, without the need for new particles or new physics, and without compromising the previous successes of LCDM. Quantum analysis of the interaction properties of baryonic particles in ‘sloping’ gravity wells shows that photon-particle cross sections can vary, depending on particle environment and that, in large deep-gravity wells, these cross sections can be much less than currently accepted values [1,2]. This purely quantum phenomenon provides an effective and unassailable solution to the dark matter problem within the LCDM framework. Additionally, a primordial formation scenario [1,3] potentially enables an “all-baryonic” universe to be observationally compliant with primordial nucleosynthesis ratios, galaxy distributions and microwave anisotropy observations, the pillars of observation that have previously required the need for a new “dark” particle. In this talk I will discuss the quantum solution to the dark matter problem. [1] Ernest, A D 2006, in Dark Matter: New Research, ed. J. Val Blain, NOVA Science, N.Y. ISBN: 1-59454-549-9 [2] Ernest A. D., 2009, J. Phys. A: Math. Theor. 42 115207, 115208 [3] Ernest A. D., and Collins, M.P., 2015, Proceedings of the International Astronomical Union, 11, pp 298-299. doi:10.1017/S1743921315006894

Tue, 11 Jul

8:00–9:15 a.m. | 9:15–10:45 a.m. | 10:45–11:00 a.m. | 11:00–11:30 a.m. | 11:30 a.m. –1:00 p.m. | 1:00–2:15 p.m. | 2:15–3:45 p.m. | 3:45–4:15 p.m. | 4:15–5:15 p.m. | 5:30–6:30 p.m. | 7:00–9:00 p.m.

Tue, 11 Jul, 8:00 a.m. to 9:15 a.m. Day ↑ | Top ↑

ESO Agreement Signing

8:00 a.m. – 9:15 a.m. @ Crawford School of Public Policy

To celebrate the creation of a strategic partnership between the Australian astronomical community and European Southern Observatory, all Annual Scientific Meeting participants are invited to two events:

  • An ESO Signing Breakfast will be held in the foyer of the Crawford School of Public Policy from 8.00-8.30am;
  • The Signing ...

More info →

Tue, 11 Jul, 9:15 a.m. to 10:45 a.m. Day ↑ | Top ↑

Session 7 – Active Galactic Nuclei

Molonglo Theatre

T29, 9:15–9:45 a.m. — Triggering AGN in galaxy clusters (Bok Prize talk)
Madeline MARSHALL, University of Melbourne

⇒ This talk is by the winner of the Bok Prize

Active galactic nuclei (AGN) play an important role in the regulation of star formation in their host galaxies and the larger scale environment. To develop a full understanding of the role of AGN, it is important to know how they are triggered. Using a semi-analytic galaxy evolution model, I investigate the predicted spatial distribution of AGN in clusters under the assumption that they are triggered by ram pressure effects. By comparing these simulated AGN to SDSS observations of relaxed clusters, I find that the observed AGN distribution can be reproduced well by ram pressure triggering, with triggering ram pressures consistent with those found to trigger star formation in hydrodynamical simulations. These findings may assist in the interpretation of cluster observations including deep multi-wavelength and integral field surveys.

T30, 9:45–10:00 a.m. — The relationship of AGN feedback by relativistic jets to the spectra of Gigahertz Peak Spectrum and Compact Steep Spectrum radio sources
Geoffrey BICKNELL, Research School of Astronomy & Astrophysics, Australian National University

Our program of 3D simulations of relativistic jets interacting with inhomogeneous interstellar media determines the resultant velocity and distribution of dense gas and the distribution of non-thermal plasma. We have utilized these simulations to determine the signatures of these interactions in the associated radio emission. Free-free absorption by the surrounding dense gas produces a turnover in the radio spectrum. The low frequency spectrum is initially steep, consistent with some spectra in the recent compilation of MWA spectra by Callingham et al. (2017). However, the spectra become flatter as the source evolves as a result of the broad distribution of optical depths produced by the jet-ISM interaction. The range of spectral indices is consistent with that of Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) sources. Moreover, the evolution of the turnover frequency is consistent with the observed anti-correlation between turnover frequency and source size discovered by Fanti et al. (1995) and O’Dea and Baum (1997). These results indicate that further studies of GPS and CSS sources can shed significant light on the physics of AGN feedback.

T31, 10:00–10:15 a.m. — Catching Feedback in the Act at the Sub-kpc Scale
Anna ZOVARO, The Australian National University

Powerful jets emerging from the black holes in active galactic nuclei (AGN) interact with the interstellar medium (ISM) as they leave the nucleus, dramatically influencing the evolution of the host galaxy. In particular, star formation is thought to be either enhanced (positive feedback) or suppressed (negative feedback) by this process. Simulations have shown that both positive and negative feedback processes may occur; however, the dominant feedback mechanism is influenced by both the precise structure of the ISM and the power of the jet, making it difficult to predict which mechanism will dominate, and in turn whether overall star formation is enhanced or suppressed. Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) sources are young radio sources with compact and often distorted morphologies resulting from the interaction of jets with a dense, inhomogeneous ISM. Potential progenitors to FR I & II radio sources, GPS/CSS sources are believed to be in an intermediate stage of evolution in which the jets have not yet broken free of the ISM and are actively suppressing or enhancing star formation. Spatially resolved observations of GPS and CSS sources on the kpc scale can therefore provide us with a valuable insight into these jet-ISM feedback processes. We present NIFS H- and K-band spatially-resolved integral field spectroscopy of the two radio sources 4C31.04 and 4C14.82. The morphology, structure and kinematics of the central gas has been analysed in conjunction with indicators of current and historical star formation to search for signatures of positive or negative feedback.

T32, 10:15–10:30 a.m. — DRAGONS: AGN quenching of high redshift star formation in ZF-COSMOS-20115
Yuxiang QIN, The University of Melbourne

Massive quiescent galaxies are thought to have formed stars rapidly at early times followed by a long period of quiescence. The recent discovery of a massive (∼1e11M⊙) quiescent galaxy, ZF-COSMOS-20115 at z ∼ 4, only 1.5 Gyr after the Big Bang, places new constraints on galaxy growth and the role of feedback in early star formation. In this talk, I will present the study of three ZF-COSMOS-20115 analogues in the DRAGONS programme, identified using the Meraxes semi-analytic model. We investigate how ZF-COSMOS-20115 analogues build stellar mass, and why they become quiescent. We find that ZF-COSMOS-20115 is likely hosted by a massive halo with virial mass of ∼1e13M⊙, having been through significant mergers at early times. These merger events drove intense growth of the nucleus, which later prevented cooling and quenched star formation. We find that the analogues host the most massive black holes in our simulation and were luminous quasars at z ∼ 5, indicating that ZF-COSMOS-20115 and other massive quiescent galaxies may be the descendants of high redshift quasars.

T33, 10:30–10:45 a.m. — Using Broad Absorption Lines to Illuminate Quasar Structure
Suk Yee YONG, The University of Melbourne

The characteristics of the spectral lines in quasars reveal information about the structure and kinematics of the broad emitting line region (BELR). A small fraction of quasars displays signature of broad absorption line (BAL) with deep absorption trough blueshifted relative to the broad emission line (BEL). This is often interpreted as a consequence of either the evolutionary or the orientation based unification models. In order to test these schemes, samples from the Sloan Digital Sky Survey are used to examine the properties of ultraviolet BELs in BAL and non-BAL quasars. Although statistical differences are found between the two populations, they exhibit rather similar BEL trends. Results from statistical analysis shows that both models are unable to completely account for the observed trends. This analysis is used to develop a new model of the quasar BELR.

Tue, 11 Jul, 10:45 a.m. to 11:00 a.m. Day ↑ | Top ↑

Poster Sparklers (1)

Molonglo Theatre

Poster numbers 1-15

Tue, 11 Jul, 11:00 a.m. to 11:30 a.m. Day ↑ | Top ↑

Morning Tea

Foyer, Crawford School of Public Policy

Tue, 11 Jul, 11:30 a.m. to 1:00 p.m. Day ↑ | Top ↑

Session 8 – Stars

Molonglo Theatre

T34, 11:30 a.m. –12:00 p.m. — Stellar Astrophysics with Cassini: Syzygies, Stardust and the Sizes of Stars (Charlene Heisler Prize talk)
Paul STEWART, Sydney Institute for Astronomy

⇒ This talk is by the winner of the Charlene Heisler Prize

The multi-national, multi-billion-dollar, Cassini mission has resulted in amazing insights into the complex Saturn system, dramatically improving our understanding of the planet, and its moons and rings. One particularly successful method employs the observation of bright stars as the planet's rings pass in front, allowing the study of the ring system. In this presentation I will demonstrate how such observations can also be used to investigate the stars themselves.

The technique is shown to be effective for measuring the spatial and spectral structure of evolved stars, including identification of molecular layers in the stellar atmosphere. It enables the recovery of high-angular-resolution 2D images of the inner regions of complex stellar systems, achieving resolutions not possible with regular telescopes. These observations are demonstrated to help constrain models of the behaviour of Mira variable stars, and to change our understanding of the inner nebula around IRC+10216.

T35, 12:00–12:15 p.m. — Detection of young stars in the large spectroscopic surveys
Marusa ZERJAL, Australian National University

Chromospheric activity is a suitable age estimator for young solar-like and cooler main sequence field stars. It manifests itself in a wide range of excess emission intensities in the strongest spectral lines. While precise dating is not possible, an order of magnitude age estimate is easily attainable from a single spectral measurement with a moderate signal-to-noise ratio and mid-range resolving power in the range from a few tens of millions of years up to a few gigayears. Today, in the era of large spectroscopic surveys targeting magnitude-limited samples, it is possible to identify a substantial number of young stars in the Solar neighbourhood with efficient unsupervised classification algorithms. In the RAVE Survey, covering over 500,000 calcium infrared triplet (Ca II IRT) spectra of more than 480,000 stars, this approach in a combination with a model-free emission measure yielded over 13,000 stars younger than 1 Gyr and almost 2000 stars younger than 100 Myr in the Solar neighbourhood (distance less than 200 pc). The strongest support for their young ages is their position in the pre-main sequence region in the color-magnitude diagram using the Gaia DR1 distances with less than 10% relative errors. Their X-ray emission is in favour of this hypothesis. The sample will be significantly extended in the future, e.g. the Galah survey will observe 1 million stars. The FunnelWeb survey, a new ambitious project with aim to cover 3 million stars down to magnitude 12 will focus on young and adolescent stars. The age estimates using the emission in the Ca II IRT and the stronger Ca II H&K lines will be improved with the Lithium 6708A line. Because the innovative TAIPAN spectrograph and the starbugs fiber positioner system will enable observations of the bright stars as well, the combination of their ages and stellar orbits using the Gaia distances and proper motions will hold a huge potential not only for the recent nearby star formation events but also for the studies of young exoplanets and their environments around the nearest stars.

T36, 12:15–12:30 p.m. — Polarisation due to rotational distortion in the bright star Regulus
Daniel Vincent COTTON, University of New South Wales

We report the first detection of polarised light due to rotational distortion in a rapidly rotating hot star, an effect first predicted nearly fifty years ago. Observations of the linear polarisation of Regulus, with two different high-precision polarimeters, range from +42 parts per million at a wavelength of 741 nm to –22 parts per million at 395 nm. The reversal from red to blue is a distinctive feature of rotation-induced polarisation. Using a new set of models for the polarisation of rapidly rotating stars we report determinations for the angular velocity, inclination, gravity and effective temperature of Regulus, as well as the position angle of the rotation axis. The conclusions are independent of, but in good agreement with, the results of interferometry. This result represents a watershed moment for stellar linear polarimetry. Previously the field has been largely restricted to studying extreme magnetic fields or material external to stars. Now we are able to probe fundamental parameters of the stellar atmosphere itself.

T37, 12:30–12:45 p.m. — Observations of radio stars with geodetic VLBI
Oleg TITOV, Geoscience Australia

Some stars have radio emission that is strong enough to be detected by geodetic VLBI facilities. Observations of these radio stars were used to link the Hipparcos (optical) and VLBI (radio) celestial reference frames in 90s. The new optical catalogue currently being compiled by Gaia will allow a more advanced link between the optical and radio reference frames to be developed. Radio stars present a good tool to calibrate the proper motions and parallaxes with high accuracy. The first results from a program to observe radio stars with the large geodetic VLBI network, which includes the Parkes and Hobart radio telescopes, are presented.

T38, 12:45–1:00 p.m. — Chasing Low Frequency Radio Bursts from Magnetically Active Stars
Christene LYNCH, University of Sydney/CAASTRO

Flaring activity is a common characteristic of magnetically active stars. These events produce emission throughout the electromagnetic spectrum, implying a range of physical processes. A number of objects exhibit short-duration, narrow band, and highly circularly polarised (reaching 100%) radio bursts. The observed polarisation and frequency-time structure of these bursts points to a coherent emission mechanism such as the electron cyclotron maser. Due to the stochastic nature of these bursts and the sensitivity of current instruments, the number of stars where coherent emission has been detected is few, with numbers limited to a few tens of objects. Observations of a wider sample of active stars are necessary in order to establish the percentage that exhibit coherent radio bursts and to relate the observed emission characteristics to stellar magnetic properties. New wide-field, low frequency radio telescopes will probe a frequency regime that is mostly unexplored for many magnetically active stars and where coherent radio emissions are expected to be more numerous. M dwarf stars are of particular interest as they are currently favoured as most likely to host habitable planets. Yet the extreme magnetic activity observed for some M dwarf stars places some doubt on the ability of orbiting planets to host life. This presentation reports the first results from a targeted Murchison Widefield Array survey of M dwarf stars that were previously detected at 100 - 200 MHz using single dish telescopes. We will discuss robust flare-rate measurements over a high dynamic range of flare properties, as well as investigate the physical mechanism(s) behind the flares.

Tue, 11 Jul, 1:00 p.m. to 2:15 p.m. Day ↑ | Top ↑


Foyer, Crawford School of Public Policy

ANITA Chapter Meeting – Sponsored by AAL

Barton Theatre

IDEA Chapter Meeting – Sponsored by CAASTRO

Molonglo Theatre

At this year's IDEA lunch meeting (Tuesday 11 Jul, 1.15pm in Molongolo Theatre) we will be presenting the 2016 Pleiades Award certificates, hearing from the 2016 Gold award winners, CAASTRO, and hearing updates to the selection criteria for the 2018 Pleiades Award.

Tue, 11 Jul, 2:15 p.m. to 3:45 p.m. Day ↑ | Top ↑

Session 9 – The Epoch of Reionization

Molonglo Theatre

T39, 2:15–2:30 p.m. — An update on the MWA EoR Experiment
Jack LINE, University of Melbourne

In this talk I will give an overview on the current status of the Epoch of Reionisation (EoR) experiment using the Murchison Widefield Array (MWA), which attempts to use cosmologically red-shifted HI emission to trace the first luminous sources in the Universe. I will highlight some of our current focus areas, such as the exquisite understanding of the telescope necessary for a detection, how well we must understand our astrophysical foregrounds and how to remove them, the effects of the ionosphere on data and polarisation, and the possible applications of redundant calibration. Throughout, I will discuss successes and progress by the collaboration to date in trying to overcome these challenges, and the current status of our analysis.

T41, 2:30–2:45 p.m. — Toward the Epoch of Reionisation: challenges and progress on the path to the Early Universe
Cathryn TROTT, ICRAR - Curtin University

The Cosmic Dawn and Epoch of Reionisation mark two crucial epochs in the formation and growth of structure in the first billion years of the Universe. Providing a bridge between the small temperature fluctuations of the CMB and structured and luminous Universe of low redshift, these epochs trace the formation and illumination of the first ionising sources of radiation, and the ionisation of the intergalactic medium. Observation of the redshifted 21-cm emission line from neutral hydrogen is a promising probe of this period, the signal of which encodes astrophysical and cosmological information. This project is particularly important for Australia, with ongoing experiments with the Murchison Widefield Array (MWA), and future host of the Square Kilometre Array (SKA). Despite its promise, detection of the signal, and study of its structure, has thus far eluded low-frequency radio telescopes. This talk discusses the challenges involved in this experiment, and the advances made over the past five years for peeling away the systematics and reaching the signal.

T43, 2:45–3:00 p.m. — Challenging EoR Challenges with Array Redundancy
Ronniy JOSEPH, Curtin University

The formation of the very first objects was accompanied by the ionisation of their surroundings and ultimately the entire Universe. This period, in which the Universe underwent this large phase change, is known as the Epoch of Reionisation (EoR), and studying it will reveal what the first objects actually were. The advent of a new generation of low frequency radio interferometers, e.g. LOFAR, the Murchison Widefield Array (MWA), and the future Square Kilometre Array, has opened a direct window into the EoR. With these telescopes we can gain insight into the cosmology and astrophysics driving structure formation in the Early Universe by studying fluctuations in the 21-cm signal emitted by neutral hydrogen. The signal is, however, hidden in foregrounds that are estimated to be 4 magnitudes stronger. In this talk I will describe the challenges of signal detection, and discuss how novel calibration strategies are crucial to its success. I will describe work I am undertaking to use the design of the MWA to improve calibration, including combining redundant and non-redundant baselines, and optimally using the information available in the data.

T45, 3:00–3:15 p.m. — Modelling High-z Galaxy Formation and the EoR with semi-analytics
Simon MUTCH, The University of Melbourne

Simultaneously modelling high-redshift galaxy formation and large scale cosmic reionization is a difficult task, but an essential one if we hope to fully leverage the combined results of future radio and IR observations. In this talk I will discuss semi-analytics as a useful and powerful compliment to other simulation methods for studying the EoR. I will then introduce Meraxes, the first semi-analytic galaxy formation model to include a temporally and spatially coupled treatment of galaxy growth and reionization. I'll also demonstrate the success of this model in reproducing a number of key observables, as well as examples of some of its predictions for galaxy sizes, and the relative importance of photo-ionisation feedback on galaxy growth. Finally, I'll discuss possible ways in which we can exploit models such as Meraxes in the future, in particular focussing on the connection between high redshift physics and low redshift/mass observations.

T47, 3:15–3:30 p.m. — Exploring Reionization With Semi-Analytics: The Escape Fraction Strikes Back
Jacob SEILER, Swinburne University

The Epoch of Reionization is a pivotal period in our cosmic history, representing the transition from a neutral post-recombination Universe into the fully ionized one we observe today. The procession of reionization is dictated by the fraction of ionizing photons, $f_\mathrm{esc}$, that escape from galaxies to ionize the inter-galactic medium, with the exact value and functional form still an open question. I explore this question using a cosmological galaxy formation model to predict the number of ionizing photons emitted, coupled with a sophisticated semi-numerical code to follow different possible Epoch of Reionization scenarios. Specifically, I investigate how changing $f_\mathrm{esc}$ affects the progress of reionization, measuring its impact on properties such as the overall duration from neutral to fully ionised, and the size of the ionised bubbles within the cosmic gas. Such predictions, when combined with future observations, will provide powerful constraints on the early evolution of gas and galaxies in the Universe.

T49, 3:30–3:45 p.m. — Bubbles at dawn
Paul Michael GEIL, The University of Melbourne

Direct detection of regions of ionised hydrogen (HII) has been suggested as a promising probe of cosmic reionisation. Observing the redshifted 21-cm signal of hydrogen from the epoch of reionisation (EoR) is a key scientific driver behind new-generation, low-frequency radio interferometers. We investigate the feasibility of combining low-frequency observations with the Square Kilometre Array and near infra-red survey data of the Wide-Field Infrared Survey Telescope to detect cosmic reionisation by imaging HII bubbles surrounding massive galaxies. While individual bubbles will be too small to be detected, we find that by stacking redshifted 21-cm spectra centred on known galaxies, it will be possible to directly detect the EoR at z ~ 9–12, and to place qualitative constraints on the evolution of the spin temperature of the intergalactic medium (IGM) at z > 9. In particular, given a detection of ionised bubbles using this technique, it is possible to determine if the IGM surrounding them is typically in absorption or emission. Determining the globally-averaged neutral fraction of the IGM using this method will prove more difficult due to degeneracy with the average size of HII regions.

Session 10 – New Stellar/Exoplanet Projects

Barton Theatre

T40, 2:15–2:30 p.m. — The FunnelWeb Survey: Exoplanet and Galactic Science in the Gaia Era
Michael IRELAND, Australian National University

The FunnelWeb survey with the TAIPAN spectrograph will begin in September this year, and will become the southern hemisphere's largest spectroscopic survey. FunnelWeb will target all stars (away from the most crowded regions) brighter than Gaia G=12, as well as selected fainter samples. I will describe the key science drivers of the survey, including TESS planet host spectra, local Galactic archaeology and a complete census of nearby young stars. I will show results from tiling simulations of the sky, demonstrating how these science goals will work together, and we will maintain a novel, adaptable prioritisation. Finally, I will describe the preferred machine learning stellar parameters approach of semi-supervised local tangent space alignment, which will be used to obtain calibrated physical parameters across the HR diagram.

T42, 2:30–2:45 p.m. — Astrophysical Standards for FunnelWeb’s Label-based Stellar Parameter Pipeline

The FunnelWeb Survey, using the TAIPAIN instrument on the UK-Schmidt telescope at Siding Spring Observatory, seeks to create a new database of spectra for every Southern Hemisphere star down to 12th magnitude. FunnelWeb will grow the number of stars with high-quality (S/N~100), moderate resolution (R~2000) spectra available in a calibrated and on-line database. The main goals of the survey include a spectral library with detailed stellar parameters (including Teff, log(g), [Fe/H] and [alpha/Fe]), an input catalogue for the TESS satellite, and identifications of young stars through Li. This talk details requirements and processes for selecting stellar standards to serve as the basis for FunnelWeb’s label based stellar parameters pipeline.

T44, 2:45–3:00 p.m. — Project PANOPTES: Finding exoplanets with digital cameras and citizen-science
Wilfred GEE, Macquarie University

Project PANOPTES is aimed at establishing a collaboration between professional astronomers, citizen scientists, and schools in order to discover a large number of exoplanets using the transit technique. An imaging unit based on consumer digital single-lens reflex (DSLR) cameras has been designed to run automatically every night, covering large parts of the sky looking for exoplanet transits. At a cost of $5000 USD, the units are a low-cost and efficient system for wide field astronomical imaging. Both science and outreach, our vision is to have dozens of units built by schools and citizen scientists in the next few years, helping make this project the most productive exoplanet discovery machine in the world. In this talk an overview of PANOPTES will be given along with a presentation of the algorithm used to overcome the complications inherent with the color filter array present in digital cameras.

T46, 3:00–3:15 p.m. — Cool stars, exoplanets and Veloce

Searching for exoplanets with the Veloce spectrograph on the AAT will begin next year. Because cool dwarf stars have a close in 'habitable zone' and a lower mass, they are the best targets for Doppler surveys to detect low-mass exoplanets. I will outline the current state of exoplanet detection around cool dwarf stars and discuss how Veloce will confirm, discover and investigate new exoplanets using the public data that will come from NASA's upcoming Transiting Exoplanet Survey Satellite (TESS).

T48, 3:15–3:30 p.m. — Veloce Rosso construction progress
James GILBERT, The Australian National University

The Veloce instrument is an ultra-stable fibre-fed R4 echelle spectrograph for the Anglo-Australian Telescope. The first phase of the project, Veloce Rosso, is currently being built at the ANU's Advanced Instrumentation & Technology Centre and will be commissioned in early 2018. The optical design has an asymmetric white-pupil format with a 100 mm beam diameter, delivering R>75,000 spectra over a 588-930 nm range for the Rosso channel. The spectrograph is housed in an environmental enclosure that maintains a positive air pressure with a stability of +/-1 mbar and is thermally stable to +/-0.1 K, for radial velocity errors equivalent to <1 m/s. I present the progress on final design and construction, including details on the environmental control system, detector system performance, and radial velocity error budget.

T15, 3:30–3:45 p.m. — The TOLIMAN space telescope
Peter TUTHILL, University of Sydney

Despite the manifest success witnessed by catalogs of exoplanetary detections climbing into the thousands, contemporary astronomy is still poorly equipped to answer the basic question of whether there are any potentially temperate planets orbiting any particular star system. This problem becomes particularly acute when considering stars in our local neighbourhood: close enough for detailed follow-up missions to characterize on decades timescales, and potentially for exploration by space probe on centuries timescales. Overwhelmingly the most promising technology to deliver a complete census of nearby habitable zone exoplanets and their properties down to Earth mass is high precision astrometry; to date a quite minor player in the exoplanetary domain. This talk will describe the TOLIMAN space telescope dedicated to astrometric detection of exoplanets, particularly targeting the Alpha Cen system. A Foundational Mission Study, jointly funded by the Breakthrough Prize Foundation and the University of Sydney, is now underway. This talk will describe the innovative principles underlying the detection strategy, and plans for construction and launch.

Tue, 11 Jul, 3:45 p.m. to 4:15 p.m. Day ↑ | Top ↑

Afternoon Tea

Foyer, Crawford School of Public Policy

Tue, 11 Jul, 4:15 p.m. to 5:15 p.m. Day ↑ | Top ↑

Session 11 – Seeing in 3D

Molonglo Theatre

T50, 4:15–4:30 p.m. — CAASTRO-3D: The ARC Centre of Excellence in All-Sky Astrophysics in 3-Dimensions
Lisa KEWLEY, Australian National University

The ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (CAASTRO-3D) aims to answer fundamental questions in Astrophysics: the origin of matter and the periodic table of elements, and the origin of ionisation in the Universe. Australia has built the 3D innovative technology and developed the expertise that will be combined by CAASTRO-3D to make a transformative impact on our understanding of the Universe. CAASTRO-3D will unify world-leading Australian optical and radio surveys with theoretical simulations and new e- Science techniques for Peta-scale data sets, while nurturing young scientific leaders and inspiring high-school students into STEM sciences through wide-reaching education and outreach programs. I will describe CAASTRO-3D and the benefits for astronomers within and outside the Centre.

T52, 4:30–4:45 p.m. — Probing effects of telescope resolution with synthetic observations of galaxy simulations
Ayan ACHARYYA, Australian National University

How well can we recover physical properties in galaxies, given telescope limitations? We produce realistic synthetic IFU data cubes from simulated isolated Milky Way type galaxies, isolating the effects of telescope and instrumentation on inferred physical quantities. In this work we specifically investigate the effect of spatial resolution on inferred metallicity gradient. I will present our new HII region models and mock data cubes followed by the results. I will also discuss the effect of spectral resolution on the inferred gradient. 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.

T54, 4:45–5:00 p.m. — The intrinsic shape of galaxies
Caroline FOSTER, Australian Astronomical Observatory

While complex, the process of galaxy formation throughout cosmic time has led to recognisably distinct types of galaxy structures. However, projection effects and limited sample sizes have so far prevented reliable measurements of the true 3D or intrinsic shape of galaxies. With the advent of multiple-integral field spectrograph technology, the data are now at hand for this fundamental property of galaxies to be measured robustly. Using SAMI Galaxy Survey data, we robustly measure the intrinsic shape of galaxies, providing a new test of galaxy formation theories. Variations of the intrinsic shape of galaxies as a function of rotational support, stellar mass and environment are explored.

T56, 5:00–5:15 p.m. — Fornax3D - Surveying the Fornax Cluster with MUSE
Richard MCDERMID, Macquarie University

Despite the recent tremendous progress in our understanding of the formation and evolution of early-type galaxies (ETGs), several key issues remain unsolved. In this respect, the nearby Fornax cluster provides a uniquely compact laboratory to study the history of ETGs and the role played by mergers and quenching in driving their size evolution and their transformation from spirals. I will present an overview of Fornax3D - a new survey using the superb capabilities of MUSE to obtain high-quality spectral maps for the central regions of all the ETGs within the virial radius of Fornax, as well as deep spectroscopic observations of their halos out to an unprecedented average distance of 4 effective radii. Using state-of-the-art stellar dynamical and population modelling, we aim in particular at better characterising the disk components of fast-rotating ETGs, constraining radial variations in the stellar initial-mass functions and measuring the stellar age, metallicity and alpha-elements abundance of stellar halos in cluster galaxies.

Session 12 – The Galactic Centre

Barton Theatre

T51, 4:15–4:30 p.m. — Gamma-rays and Gas in the Galactic Centre
Rebecca BLACKWELL, The University of Adelaide

Towards the Galactic Centre, HESS (the High Energy Stereoscopic System) has observed a diffuse ridge of Very-High-Energy (VHE) gamma-rays, including a hard spectrum central source referred to as the Galactic Centre PeVatron. If these VHE gamma-rays are hadronic in origin, being produced by Galactic Centre Cosmic Ray interactions, then an understanding of the region's potential target material is necessary. We have observed the Central Molecular Zone with the Mopra radio telescope in three lines of Carbon Monoxide, a diffuse gas and common tracer for molecular hydrogen. Here we present the results of our comparison between the gamma-rays and the gas, highlighting the implications of variation across the region.

T53, 4:30–4:45 p.m. — Shock Waves in the Unusual Galactic Centre Molecular Clouds
Andrew LEHMANN, Department of Physics and Astronomy, Macquarie University

The molecular clouds near the centre of the Galaxy are ideal testbeds for star formation processes due to their atypical properties. Consistently high gas temperatures (>50 K) have been found throughout this region, demanding a global heating mechanism. Large linewidths suggest that strong turbulence is present, and its dissipation naturally explains the high temperatures. We search for chemical signatures of turbulent damping by modeling two-fluid magnetohydrodynamic shocks that are expected to dominate the dissipation. By comparing shock chemistry to equilibrium cloud chemistry, we identify signatures of shocked gas in enhancements of various species. In particular, the abundances of sulphur-bearing species SO, SO2 and H2S are sensitive to the hot shocked gas, even if the shock fronts only occupy 0.1% of the line-of-sight column density. We discuss how observations of particular species could constrain the physical parameters of Galactic Centre molecular clouds, such as the cosmic-ray ionization rate and gas volume density.

T55, 4:45–5:00 p.m. — Atomic Hydrogen Clouds Tracing the Galactic Nuclear Outflow
Enrico DI TEODORO, Australian National University

We present the results of a new deep survey of neutral hydrogen above and below the Galactic Center with the Green Bank Telescope, extending up to Galactic latitude | b | < 10 degrees. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of 1.5 kpc from the Galactic Plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities | VLSR | < 350 km/s, typical sizes of few tens pc and neutral hydrogen masses of a few hundreds solar masses. We model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocities 300 km/s < Vw < 400 km/s inside a bi-cone with opening angle α > 140 degrees. These clouds likely represent the cold gas component entrained in the nuclear wind driven by our Galaxy.

T57, 5:00–5:15 p.m. — CO Observations of the Ursa Major Molecular Clouds at High Galactic Latitudes
Qingzeng YAN, ICRAR/Curtin

We present the priliminary result of a CO Survey for the Ursa Major Melcular Clouds, whose center is about (145°, 38°). We observed three CO isotropic lines, including 12CO (1-0), 13CO (1-0), and C18O (1-0). No C18O (1-0) emission is detect. The overall distribution of CO emission largely overlap with dust emission (IRAS 100 μm), having little common area with HI. We identified molecular cores with Duchamp, and the power-law index for the core mass function (CMF) is α=1.87±0.08, which is consistent with previous results derived from low-density moleuclar clouds.

Tue, 11 Jul, 5:30 p.m. to 6:30 p.m. Day ↑ | Top ↑

ATNF Town Hall – Sponsored by CASS

Foyer, Crawford School of Public Policy

Tue, 11 Jul, 7:00 p.m. to 9:00 p.m. Day ↑ | Top ↑

Rainbow Astronomy Dinner – Sponsored by ICRAR

Location TBA

The Rainbow Astronomy social dinner (for those who identify as LGBTI+, allies are also welcome) will run Tuesday 11th July. We will meet in the foyer at 7pm and walk to dinner. If you have strong feelings or ideas about how to organise this event please Sarah Brough ( as soon as possible.


Dinner is at the Roti House (Ernst & Young Building, 4/121 Marcus Clarke St, Canberra

Wed, 12 Jul

8:00–8:50 a.m. | 9:00–10:00 a.m. | 10:00–10:30 a.m. | 10:30–11:00 a.m. | 11:00–11:30 a.m. | 11:30 a.m. –1:00 p.m. | 1:00–2:15 p.m. | 2:15–4:00 p.m. | 4:00–4:30 p.m. | 4:30–5:30 p.m. | 5:30–8:45 p.m.

Wed, 12 Jul, 8:00 a.m. to 8:50 a.m. Day ↑ | Top ↑

Heads' and Directors' Meeting

Griffin Seminar Room

This session is strictly closed to all except the heads and directors of Australian astronomical institutions.

Wed, 12 Jul, 9:00 a.m. to 10:00 a.m. Day ↑ | Top ↑

Session 13 – Cosmology

Molonglo Theatre

T58, 9:00–9:15 a.m. — Constraints on the nature of Dark Energy from OzDES
Chris LIDMAN, Australian Astronomical Observatory

We present results from the first four years of OzDES, a six-year programme to obtain redshifts for objects in the Dark Energy Survey (DES) supernova fields with the 2dF fibre positioner and AAOmega spectrograph on the Anglo-Australian Telescope. At the end of four years, OzDES has spectroscopically confirmed around 150 SNe, and has measured redshifts for 22,000 objects, including the redshifts of 4,150 SN hosts. We use a small subset of the data from the first three years of the survey to demonstrate that we already provide competitive constraints on the dark energy equation of state parameter.

T59, 9:15–9:30 a.m. — Reverberation Mapping in Bulk with DES/OzDES
Natalia Eiré SOMMER, Research School of Astronomy and Astrophysics, Australian National University

It has recently been shown that active galactic nuclei (AGN) may be possible to use as standardisable candles utilising the method of reverberation mapping. Their luminosity allows them to be seen at high redshifts (z>2) using even medium-sized ground-based telescopes, used by for instance the Dark Energy Survey (DES) and the Australian Dark Energy Survey (OzDES). These are together targeting AGN for this reverberation mapping purposes, and expect to increase the number of AGN with reverberation mapping estimates by a very significant amount on world basis. In this talk I will present the current state of the DES/OzDES reverberation mapping project, the challenges we are facing, and the very promising results we are expecting to obtain.

T60, 9:30–9:45 a.m. — A new CMB lensing measurement from 500 square degrees of SPTpol data
Federico BIANCHINI, University of Melbourne

The path of cosmic microwave background (CMB) photons is gently deflected by large-scale structure (LSS) in the universe through a process called weak gravitational lensing. This effect introduces non-Gaussian features in the observed CMB temperature and polarisation anisotropies which can be exploited by high-sensitivity experiments to reconstruct the projected mass distribution out to the surface of last scattering. Thus, CMB lensing offers a unique window on the dark universe by being sensitive to the geometry and growth of LSS, which in turn can place tight constraints on the sum of neutrino masses and on the mechanisms sourcing the cosmic acceleration. In this talk, I will present a new measurement of the CMB lensing potential power spectrum using data from 500 deg^2 of the southern sky observed with SPTpol, a millimeter-wavelength polarisation-sensitive receiver installed on the South Pole Telescope.

T61, 9:45–10:00 a.m. — A Blinded Determination of H_0 from Low-Redshift Type Ia Supernovae, Calibrated by Cepheid Variables
Bonnie ZHANG, Australian National University

Presently a $>3\sigma$ tension exists between values of the Hubble constant $H_0$ derived from the Planck analysis of CMB fluctuations, and local measurements using type Ia supernovae (SNe Ia). We perform a blinded reanalysis of Riess et al. 2011 to measure $H_0$ from low-redshift SNe Ia, calibrated by Cepheid variables and geometric distances. Our end-to-end analysis starts from available CfA3 and LOSS photometry, providing an independent validation of Riess et al. 2011. We obscure the value of $H_0$ throughout our analysis and the referee process, because calibration of SNe Ia requires a series of often subtle choices, and the potential for results to be affected by human bias is significant. Our analysis departs from that of Riess et al. 2011 by incorporating the covariance matrix method adopted in SNLS and JLA to quantify SN Ia systematics, and by including a simultaneous MultiNest fit to all SN Ia and Cepheid data. These differences increase the relative error in H0 to 4.3% statistical, 1.1% systematic, 4.4% total: larger than previous analyses of the same data set (3.3% total in Riess et al. 2011, and 3.4% total in the Efstathiou 2014 reanalysis). Our error budget for $H_0$ is dominated by statistical errors due to the small size of the supernova sample.

Wed, 12 Jul, 10:00 a.m. to 10:30 a.m. Day ↑ | Top ↑

Poster Sparklers (2)

Molonglo Theatre

Poster numbers 16 and above

Wed, 12 Jul, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Foyer, Crawford School of Public Policy

Wed, 12 Jul, 11:00 a.m. to 11:30 a.m. Day ↑ | Top ↑

Ellery Lecture

Molonglo Theatre

The Ellery Lectureship will be announced shortly.

Wed, 12 Jul, 11:30 a.m. to 1:00 p.m. Day ↑ | Top ↑

ASA Annual General Meeting

Molonglo Theatre

Wed, 12 Jul, 1:00 p.m. to 2:15 p.m. Day ↑ | Top ↑


Foyer, Crawford School of Public Policy

EPOC Chapter Meeting – Sponsored by Swinburne University

Barton Theatre

- Rob Hollow will give an over of EPOC 2016-2017 activities + 2017-2018 plans 

- Tom Carruthers (Questacon) will speak on National Science Week 

- Candice Lim (CSIRO) will speak on Scientists in Schools 

- Ingrid McCarthy (CBRIN) will speak on the Inspiring Australia scheme

- We will end with a Q&A and time for discussions.  

NCRIS Data & Computing Facilities Meet Astronomers – Sponsored by AAL

Molonglo Theatre

Speakers in this session will be:

  1. Dr. Andrew Treloar (Director of Technology, ANDS)
  2. Dr. Michelle Barker (Deputy Director, NeCTAR)
  3. Ian Duncan (Executive Director, RDS)
  4. Dr. Neil Stringfellow (Executive Director, Pawsey)
  5. Dr. Ben Evans (Associate Director, NCI)
  6. Prof. Jarrod Hurley (Swinburne)

Wed, 12 Jul, 2:15 p.m. to 4:00 p.m. Day ↑ | Top ↑

Session 14 – Extra-galactic Transients

Molonglo Theatre

T62, 2:15–2:30 p.m. — The Properties of The Fast Radio Burst population
Jean-Pierre MACQUART, International Centre for Radio Astronomy Research/Curtin University

Fast Radio Bursts (FRBs) are millisecond-duration transient astronomical signals whose origin and extreme energetics are subjects of intense debate. It is now known that FRBs emanate at cosmological distances and it is inferred that they release in excess of 10^40 erg in the radio band alone. Until now, progress been has hampered by the difficulty of detecting sufficient FRBs to accumulate adequate statistics on their properties.  The Commensal ASKAP Fast Transients (CRAFT) survey has been accumulating detections of FRBs at a rate of an event every 1-2 days. I will discuss the implications of our CRAFT detections for the energetics, the implications of the fluence distribution (i.e. source counts) on their redshift distribution, and the viability of using FRBs to chart the distribution of the missing baryonic matter that pervades intergalactic space. This talk is intended to adjoin the CRAFT talk of Ryan Shannon.

T64, 2:30–2:45 p.m. — Discovering radio transients using Triggered and Targeted observations
Gemma Elizabeth ANDERSON, ICRAR - Curtin University

As we approach the era of the Square Kilometre Array (SKA), astronomers are investigating how to utilise these facilities for radio transient astronomy. The majority of radio transient studies have focused on blind searches for transients in radio surveys and archival data. While important steps have been made towards optimising and automating such searches, these studies have demonstrated that radio transients are rare and faint. In this talk I will present two alternative methods for radio transient discovery, "triggered" and "targeted" observations, which can be used to supplement the blind survey approach. Both of these techniques focus on performing radio observations of sky regions for which we expect to find radio transients. "Triggered" observations are obtained by telescopes capable of rapidly responding to transient alerts, which automatically repoint and begin collecting data within minutes of discovery. For example, the Arcminute Microkelvin Imager (AMI) rapidly-responds to Swift-detected high-energy transients, such as gamma-ray bursts and flare stars, and has successfully obtained some of the earliest detections of transient radio emission from such objects. The Australia Telescope Compact Array (ATCA) now has a similar system installed, which began operations during the current observing semester. This makes ATCA the most sensitive radio telescope capable of triggered observations. The "targeted" observational technique involves radio monitoring of nearby, face-on galaxies. Such observations are sensitive to transient radio jets from black holes accreting at, or above, the Eddington limit, with the additional benefit of providing many potential sources within a single field-of-view. I will demonstrate the validity of this technique through the recent discovery of a radio transient, likely the radio jet from an outbursting black hole, detected as part of a two-year, Very Large Array monitoring campaign of M81. Both "triggered" and "targeted" observations illustrate important techniques for radio transient discovery that can be employed by the SKA.

T66, 2:45–3:00 p.m. — KEGS - The Kepler Extra-Galactic Survey

I will give an overview of the Kepler Extra-Galactic Survey (KEGS), a program using Kepler to search for supernovae, active galactic nuclei, and other transients in galaxies. To date we have found 22 supernova, and with 2 more years (through 2018) planned, including the forward-facing C16/C17, we hope to discover 20 - 30 more SN. The 30-minute cadence of Kepler has reveales subtle features in the light-curves of these supernova not detectable with any other survey -  including, shock break-out in a large number of SN, improving our understanding of supernova progenitors. We can also search in nearby galaxies for very fast and faint transients, filling in a previously unaccessible parameter space.

T68, 3:00–3:15 p.m. — DECam detection and Keck Spectroscopy of Ongoing High Redshift Superluminous Supernovae
Chris CURTIN, Swinburne

We have collected deep u-band imaging of a number of southern fields using the DECam at CTIO as part of the Survey Using DECam for Superluminous Supernovae (SUDSS). Using color selection, enhanced by the large wavelength range of the available data, including our u-band contribution, we have generated large catalogs of high redshift (z ~ 2-4) Lyman Break Galaxies (LBGs). Our LBG selection and monitoring technique enables the efficient identification of high redshift transients, namely superluminous supernovae (SLSNe). When taking spectra, we search for rising, or near peak supernovae (less than a few weeks old, restframe). At present, in fields with regular ongoing coverage, we can select ~10 candidates per field at short notice that meet our criteria. This is a lower limit on the detection rate, though our spectroscopic follow up campaign will enable a measurement of the ratio of SLSNe to candidates. The deep, Keck spectra also enable SLSNe classification and offer a wealth of information on the physics of the individual events. In addition, the data are useful toward determining SLSN rates at different redshifts, linking SLSN types to their far ultraviolet light curve behaviors for both past and future photometric identification, and possibly identifying other types of superluminous, high redshift transients, such as tidal disruption events.

T70, 3:15–3:30 p.m. — DASH: Deep Learning for the Automated Spectral Classification of Supernovae
Daniel MUTHUKRISHNA, Australian National University

We have reached a new era of ‘big data’ in astronomy with surveys now recording an unprecedented number of spectra. The Australian Dark Energy Survey (OzDES) is currently in the process of spectroscopically measuring thousands of supernovae. To meet this new demand, novel approaches that are able to automate and speed up the classification process of these spectra is essential. To this end, I have developed a software package, DASH, that uses deep learning to classify supernova spectra. The difficulties in this classification lie in the contamination from the host galaxies, and the degeneracies with type, age, and redshift of each supernova. DASH minimises the human-time involved in supernova classification, while also limiting human-bias and error so that any spectrum can be objectively, quickly, and accurately classified. It is over 100 times faster than other classification alternatives, being able to classify hundreds of spectra within seconds. DASH has achieved this by employing a deep neural network built with Tensorflow to train a matching algorithm. It is available as an easy to use graphical interface, and as an importable python library on GitHub and PyPI with ‘pip install astrodash’.

T72, 3:30–3:45 p.m. — The Zadko Telescope: Exploring the transient Universe
David Martin COWARD, University of Western Australia

The Zadko Telescope is a 1 m robotic telescope, situated in the state of Western Australia about 80 km north of Perth. The facility plays a niche role in Australian astronomy, as it is the only meter class facility in Australia dedicated to automated follow-up imaging of alerts or triggers received from different external instruments/detectors spanning the entire electromagnetic spectrum. Furthermore the location of the facility at a longitude not covered by other meter class facilities provides an important resource for time critical projects. We review the core science projects, which include automated rapid follow-up of gamma ray burst (GRB) optical afterglows, imaging of neutrino counterpart candidates from the ANTARES neutrino observatory, photometry of rare (Barbarian) asteroids, supernovae searches in nearby galaxies. We discuss participation in the optical follow-up of gravitational wave candidates from the U.S. and European gravitational wave observatory network, and present first tests for very low latency follow-up of fast radio bursts.

T74, 3:45–4:00 p.m. — Searching for Ultra-Violet Gravitational Wave Counterparts with GLUV
Ryan RIDDEN-HARPER, Australian National University

Gravitational wave (GW) astronomy is a rapidly growing field, with multi-wavelength follow-up observations. A telescope network has been developed to search for GW counterparts, supported by theoretical models, however, they largely exclude ultra-violet (UV) wavelengths. This exclusion is not a reflection of low impact data, but rather, a lack of UV capable surveys. I will discuss the mission concept of GLUV, a balloon-borne, high-cadence UV survey telescope under development at the ANU; and examine the value of UV photometry in detecting and constraining properties of GW events.

Session 15 – Star Formation

Barton Theatre

T63, 2:15–2:30 p.m. — Star Formation, Turbulence, and Transport: A Unified Model of Galaxy Discs
Mark KRUMHOLZ, Research School of Astronomy and Astrophysics, Australian National University

In this talk I present a new analytic model for the structure of gaseous galactic discs. The model unifies the regulation of star formation, driving of turbulence, and radial transport of gas into a single framework. The model naturally reproduces a number of observations, including the Kennicutt-Schmidt Law, the relationship between galaxies star formation rates and gas velocity dispersions, and the rates of radial transport required to fuel star formation in galaxy centres.

T65, 2:30–2:45 p.m. — Star formation within one parsec of the supermassive black hole at the Galactic Centre
Mark WARDLE, Macquarie University

The tidal field of supermassive black holes has long been thought to suppress nearby star formation. We present radio continuum and SiO observations of the inner 2 pc of the Galaxy that reveal that low-mass star formation is occurring in molecular clouds within 1 pc of Sgr A*, the 4 million solar mass black hole at the centre of the Galaxy. We use the virial theorem, extended to account for the tidal field of Sgr A*, to show that the high ambient pressure at the galactic centre allows compact clouds to be stable at densities far below the Roche density, and that gravitational collapse can be triggered by external turbulence or ram pressure.

T67, 2:45–3:00 p.m. — Star formation and physical processes in galaxies at radio wavelengths
Anna D KAPINSKA, International Centre for Radio Astronomy Research (ICRAR)

Using the recent Galactic and extragalactic All-sky Murchison Widefield Array survey (GLEAM) I investigate radio continuum emission from six major members of the nearby Sculptor Group. Radio emission from normal galaxies, and its characteristic, is still rather poorly understood, yet it has been proposed as one of the most accurate star formation rate (SFR) tracers. In this talk I will report on the detections of the nearby Sculptor Group starburst and star-forming galaxies at radio frequencies below 250MHz, and discuss detectability of normal galaxies at radio wavelengths. Furthermore, I will present broadband multi-frequency spectral energy distributions (SEDs) of these galaxies. I model physical processes that contribute to the observed radio continuum and derive star formation histories (SFHs). The SEDs show a variety of shapes which I will discuss with respect to the SFHs and physical conditions of the galaxies (Kapinska et al. 2017, Kapinska et al. subm). Finally, I will compare these results to the predictions from the FIR/radio correlation and derivations of SFRs, with an additional mote that at low redshifts even low level AGN emission follows this correlation and as such may masquerade as star forming galaxies (Wong, w/Kapinska et al. 2016).

T69, 3:00–3:15 p.m. — Hunting for cold gas with HI absorption
Helga DENES, Commonwealth Scientific and Industrial Research Organisation/ The Australian National University

An important process on the way to star formation is the transformation of atomic gas to molecular gas. A key to understanding this process is mapping the temperature and density variations of the cold neutral medium (CNM) across the Galaxy. The best place to start investigating the CNM are neutral hydrogen (HI) self absorption (HISA) clouds. They are found throughout the Galaxy where cold HI clouds are located in front of warmer HI emission and they reveal the spatial structure of the cold atomic gas. However, to get a good handle on the physical properties of the cold gas HI absorption measurements against bright background sources are needed. To do this, we mapped the Riegel-Crutcher cloud, one of the most famous HISA regions located in front of the Galactic Centre, in HI absorption. I will present our HI absorption survey against 46 background continuum sources and discuss what we can learn from these about the physical conditions of the CNM.

T71, 3:15–3:30 p.m. — Investigation of Coherent Star Formation in SAMI Galaxies
Gregory Bevan GOLDSTEIN, Macquarie University

The radial profile of H_alpha is studied in a sample of 401 galaxies to investigate the finding of coherent star formation (SF) in galaxies reported by Nelson et al, 2016 (subsequently N1). The profiles are studied for galaxies on the the star formation main sequence (MS) as defined by Renzini and Peng, 2015, for galaxies above the MS, and also as galaxies drop off the MS and become quenched. The star formation rate (SFR) of each galaxy is used to classify each galaxy based on distance from the MS. Coherent star formation refers to the distribution of star formation in a galaxy disk, whereby if SF is found to be low in one area (say the centre), it will also be low in the periphery of the galaxy and elsewhere in the disk; and conversely if a galaxy has high overall SF, so that it is above the SF main sequence, then SF will be found to be high in all areas of the galaxy. Coherent star formation may point to the presence of a galaxy-wide throttle or controller of SF, that operates in addition to well-established quenching mechanisms that act locally, eg the bulge at the centre, or ram pressure stripping at the galaxy periphery. The radial profile for galaxies in the group above the MS shows H_alpha is elevated at all radii; and for galaxies in the two groups below the MS, H_alpha is depressed at all radii. These results support the finding of N1 that star formation is coherent across the disks of star forming galaxies. However the profiles in galaxies above and below the SFMS are somewhat less coherent than N1 reported, because (a) in some galaxies falling below the MS there is evidence of greater offset from the MS in the inner compared to the outer disk, consistent with inside-out quenching; and (b) in the above-MS galaxies, while star formation is coherent, the inner/outer offset ratio progressively increases from 0.44 for low-mass galaxies to 1.42 for high mass galaxies. This increase is consistent with more central concentration of star formation with increasing galaxy mass. Coherent star formation is consistent with theory and observations supporting strangulation of gas supply as a principal quenching mechanism, including the theory of cosmic web detachment. Reference: Nelson E.J. et al., 2016, ApJ, 828, 27

T73, 3:30–3:45 p.m. — Unravelling the prestellar phase of star formation using Planck cold cores
John Alexander Pena LOPEZ, University of New South Wales, Australia

A comprehensive understanding of star formation remains an unsolved problem in astronomy today. While it is well established that stars form within molecular clouds, there is great uncertainty on the physical and chemical properties during the earliest stage of this process, known as the prestellar phase, which is just before a dense core collapses to form a protostar. A viable solution to understanding this phase, has presented itself in the form of an all-sky census of dusty objects, know as the Cold Clump Catalogue of Planck Objects, which combines data from both Planck and the Infrared Astronomical Satellite. We have focused our attention on a sub-sample of this catalogue, known as the early cold cores, which contains the most reliable data and in which all cores have a temperature of less than 14 K. These cold cores have been followed up with molecular line observations from the Purple Mountain Observatory, Caltech Submillimeter Observatory and Atacama Pathfinder Experiment; all of which are radio telescopes. I present an overview of the work done so far, as well as early results interpreting the physical properties of the cores themselves.

Wed, 12 Jul, 4:00 p.m. to 4:30 p.m. Day ↑ | Top ↑

Afternoon Tea

Foyer, Crawford School of Public Policy

Wed, 12 Jul, 4:30 p.m. to 5:30 p.m. Day ↑ | Top ↑

Session 16 – Globular Clusters and the Magellanic Cloud

Molonglo Theatre

T75, 4:30–4:45 p.m. — Investigating globular cluster abundance anomalies in SMC Intermediate-Age Star Clusters
Carolina SALGADO, Australian National University

One of the main unsolved problems in the stellar population field is the origin of the observed abundance anomalies in globular cluster stars. An important contribution to its solution is to know if the anomalies are restricted solely to massive star clusters formed at earliest epochs or if they can occur in younger massive star clusters. The SMC is an ideal location to explore this question because it hosts massive star cluster with ages between 6 and 11 Gyr. Using VLT/FORS2 observations we have investigated the anti-correlation and distribution of CH and CN band strengths through the measurement of CH (λ 4300) and CN (λ 3880, 4215) in red giants in Lindsay 1 and NGC 339. The metallicity and luminosity of these clusters is comparable to Galactic globular clusters (GGCs) but they are notably younger, their ages are ~ 7.5 and ~ 6 Gyr respectively. Due to the possibility of evolutionary mixing on the red giant branch, the existence of CN-CH anti-correlation is not sufficient in itself to indicate the presence of abundance anomalies. Consequently, we have investigated the Na, CN correlation through the measurement of sodium D-lines using data from GMOS-S observations. These data provide crucial additional information to establish the existence or absence of the abundance anomaly phenomenon in these younger objects. Our results will provide an accurate context for studying the problem of the origin of the anomalies by constraining the age dependence in the unexplored 6-11 Gyr age range.

T77, 4:45–5:00 p.m. — Tracing extratidal stars of globular clusters
Colin NAVIN, Macquarie University

We conducted a search for extratidal cluster halo stars around the Galactic globular clusters NGC~1851, M3 (NGC~5272), M13 (NGC~6205), $\omega$~Cen (NGC~5139), NGC~6541, M70 (NGC~6681) and M55 (NGC~6809). We identified a number of probable extratidal cluster halo stars: four for NGC~1851, eight for M3, 12 for M13, 20 for $\omega$~Cen, six for NGC~6541, one for M70, and six for M55. Distances of the stars ranged from $\sim$3 to $\sim$22 times the tidal radius of their probable parent cluster. The membership of the four stars of NGC~1851 was confirmed with further analysis of the AAOmega spectra. These results support previous indications that these clusters are surrounded by extended stellar halos. We also compared the destruction rates corresponding to the observed mass loss with destruction rates predicted by theoretical studies. For NGC~1851 we found they are comparable to some predictions, but for all other clusters we found that they are, generally, significantly higher. If these destruction rates are correct and other clusters are also found to have higher destruction rates than predicted, it may imply that the initial masses of globular clusters were higher than we currently expect, or the initial mass functions may be different. It may also imply that the proportion of Galactic halo stars contributed by globular clusters is larger than we current predictions.

T79, 5:00–5:15 p.m. — Mapping the Magellanic Outskirts with DECam
Dougal MACKEY, Australian National University

The Large and Small Magellanic Clouds constitute a unique laboratory for understanding how interactions between galaxies shape their evolutionary histories. I will present the latest results from a project using the Dark Energy Camera (DECam) to map the extreme outskirts of the Magellanic system for the first time at ultra-low surface brightness. We have discovered a spectacular array of structural distortions in the periphery of the LMC that are likely due to a recent close encounter between the Clouds. In addition, our survey is providing new insights into the unusual low-density low-metallicity star formation occurring in the Magellanic Bridge of stripped HI gas.

T81, 5:15–5:30 p.m. — An X-ray Expansion and Proper Motion Study of a Young Supernova Remnant in the Large Magellanic Cloud
Quentin ROPER, Western Sydney University

Using archival Chandra data consisting of a total of 78.46 ksec over two epochs seven years apart, we have measured the expansion of the young (400 years old) type~Ia Large Magellanic Cloud supernova remnant (SNR) J0509-6731. We use radial brightness profile matching to detect proper-motion expansion of this SNR, and estimate an expansion speed of 7,500$\pm$1,700~km/s. This is one of the only proper motion studies of extragalactic SNRs expansion able to derive an expansion velocity, and the only such study of an extragalactic SNR to yield positive results in the X-rays. We also briefly compare this result with a recent radio survey, and find that our results predict a radio spectral index $\alpha$ of 0.67$\pm$0.07. This value is consistent with high frequency radio observations of MCSNR J0509-6731.

Session 17 – The Interstellar Medium

Barton Theatre

T76, 4:30–4:45 p.m. — Galactic scale feedback from relativistic jets
Dipanjan MUKHERJEE, Australian National University

Relativistic jets from AGNs are an important driver of feedback in galaxies. They first interact with the host galaxy's ISM before breaking out to larger scales, significantly affecting the galaxy's morphology and evolution. We shall present the results of our recent 3D relativistic hydrodynamic simulations, performed on scales of several kpc, of AGN jets interacting with an inhomogeneous turbulent ISM of a high red-shift galaxy. Our simulations addresses the local gas physics, which is often missed in large scale cosmological simulations due to lack of sufficient resolution. The relativistic jet initially couples strongly with the turbulent ISM, driving fast moving lateral outflows of dense gas. The resultant outflows though strong, do not escape the galaxy, supporting a galactic fountain scenario of feedback, rather than a blow out phase as envisaged in earlier models. We compare the effect of jet power and ISM density on feedback efficiency. We show that low power jets remain confined within the host for a longer time. Such confined jets drive shocks through the ISM which can potentially quench star formation on a large scale. We also evaluate the expected luminosities of some optical line emissions (H-alpha and OIII) and in X-ray bands from the shock excited gas, which can be compared with results from multi-wavelength IFU & X-ray observations of these systems.

T78, 4:45–5:00 p.m. — Magnetic fields of a Galactic Supershell
Alec THOMSON, The Australian National University

Magnetic fields are known to play a crucial role in the interstellar medium (ISM) of the Galaxy. Radio polarimetry provides an excellent method of measuring magnetic fields in the ISM. Galactic supershells are some of the largest structures in the Galactic ISM, and should perturb the structure of Galactic magnetic fields. I will present my work determining the structure and strength of magnetic fields associated with a Galactic supershell. This was achieved by modelling the effect of the magnetic fields on polarised radio continuum emission, and fitted using maximum likelihood techniques.

T80, 5:00–5:15 p.m. — Gas Temperature Demography and the HI-to-H2 Transition in the Magellanic Clouds
Katie JAMESON, Australian National University

Not only is the transition from warm to cold neutral gas a rate limiting step to the formation of molecular gas, but it appears to influence star formation efficiency globally and we still do not understand how metallicity affects this transition. Given their proximity and low metallicity, the Magellanic Clouds provide the ideal laboratory to study the evolution of gas in the interstellar medium. We present first results from a new HI and OH absorption line study using the ATCA to measure the warm-to-cold atomic fraction and the atomic-to-molecular transition in the Large and Small Magellanic Clouds (LMC and SMC, respectively). The survey targets 48 sources in the LMC and 29 sources in the SMC, which doubles the number of existing observations and with at least $3\times$ greater sensitivity and higher spectral resolution than previous absorption line measurement studies. We decompose the emission and absorption spectra using the autonomous gaussian decomposition software GaussPy (Lindner et al. 2015), which allows us to measure the spin temperature and optical depth of the HI gas. These measurements of the optical depth allow us to constrain the amount of ``CO-faint'' gas that is optically thick HI gas. Initial analysis indicates that we measure higher spin temperatures than the previous studies (Dickey et al. 1994, Marx-Zimmer et al. 2000), and cold atomic gas fractions of $\sim20\%$. We currently have no detections of OH absorption and an upper limit on the column density of molecular gas in the targeted lines of sight of $\sim$few $\times10^{22}$ cm$^{-2}$, which is consistent with the dust-based molecular gas estimates.

T82, 5:15–5:30 p.m. — Shining Light on the Dark Milky Way: Probing our Galaxy’s Hidden Gas
Van Hiep NGUYEN, Macquarie University

Many studies have proved the existence of the “dark interstellar medium” (dark ISM) which is not detected by traditional radio emissions from atomic hydrogen (HI) and carbon monoxide (CO) molecules. In recent years, OH has emerged as a powerful indicator of dark-ISM. In this study, we use HI and OH data from the Arecibo Millennium survey (Heiles and Troland 2003) which observed absorption and emission pairs towards 79 extragalatic radio continuum sources. The Λ-doubling transitions of ground-state OH at 1665.402 and 1667.359 MHz were observed along with HI towards 48 of the 79 survey positions. By newly reducing this unpublished data, OH absorption was detected in 23 linesof-sight, we find that the OH 1665 and 1667 lines satisfy the optically thin assumption with the optical depth τ less than 0.25 and they are in general not in Local Thermal Equilibrium. By comparing the thermal dust data from Planck satellite (Release 1.2) and the Sloan Digital Sky Survey (Schlafly et al. 2011) with HI data from Millennium survey, we confirm the tight linear correlations between optical depth τ353, dust radiance R, reddening E(B-V) and the total proton column density N(H). We estimate the molecular hydrogen column densities N(H2)=½[N(H)-N(HI)] from these linear relationships and hence the OH abundance ratio XOH=N(OH)/N(H2), for which few literature measurement exist. The XOH ratios derived from the three N(H) proxies are consistent and appear to be constant around 5.0×10-6. Since these results are obtained in a wide ranges of longitude l and latitude b with some sightlines through the Galactic plane, it suggests that OH main lines are excellent tracers of molecular gas in the interstellar medium including regimes where the usefulness of CO is compromised. Keywords: ISM: clouds - ISM: molecules - dust, reddening, extinction

Wed, 12 Jul, 5:30 p.m. to 8:45 p.m. Day ↑ | Top ↑

Harley Wood Public Lecture

Registration required

5:30 p.m. – 8:30 p.m. @ Questacon

This event is sponsored by ASTRO-3D.

The annual Harley Wood Public Lecture wiil take place at Questacon on Wednesday, 12 July. This will be preceded by the launch of ASTRO-3D:
5.30-7.30pm: ASTRO-3D Launch
7.30-8.30pm: Harley Wood Lecture

Transportation to the event from the conference venue will ...

More info →

Transportation to Questacon

Departs: Crawford Building

Harley Wood Lecture


7:30–8:30 p.m. — Extreme Events - Exploring the Transient Universe (Harley Wood Lecture talk)
Tara MURPHY, University of Sydney

⇒ This talk is by the winner of the Harley Wood Lecture

Transient astronomical objects (those that appear and disappear rapidly) signal some of the most extreme events in the Universe: events such as stars dying, the moment a black hole forms, or the collision of two neutron stars. Detecting these rare events pushes our telescopes and analysis techniques to the limit, but the reward is insights into extreme physics that can’t be obtained in any other way. I will discuss how new telescopes are letting us see the sky in new ways and how the way we do science is changing in the era of big data.

Transportation to ANU Campus

Departs: Questacon

Thu, 13 Jul

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

Thu, 13 Jul, 9:00 a.m. to 10:15 a.m. Day ↑ | Top ↑

Session 18 – Cosmology with, and Evolution of, Galaxies

Molonglo Theatre

T83, 9:00–9:15 a.m. — The Taipan Galaxy Survey
Andrew HOPKINS, Australian Astronomical Observatory

Taipan is a new multiobject spectroscopic survey with the UKST. The UKST has been completely refurbished to facilitate the project, and a novel positioning system using the AAO's "starbug" technology allows parallel positioning of up to 150 optical fibres in just a few minutes. With this new system, the Taipan survey aims to measure up to 1.5M galaxies in the coming 4-5 years. This will enable a significant improvement on the measurement of the Hubble parameter, the most extensive map of the mass distribution and motions in the local Universe using peculiar velocities, and understanding the role of mass and environment in the evolution of the galaxies. Taipan will have strong legacy value through complementing current and planned surveys of the southern sky, and it will be a key spectroscopic resource for years to come.

T84, 9:15–9:30 a.m. — Taipan Peculiar Velocity Survey

One of the major science goals of the upcoming Taipan survey is to make the most extensive map of the mass distribution and motions in the local Universe. In this talk, I will outline the peculiar velocity survey aspect of Taipan in the context of: 1) mapping the density and velocity fields in the local Universe to unprecedented precision; 2) testing the cosmological model with peculiar velocities; 3) testing models of gravity with precise measurements of the growth rate of structure. I will present some of the key advantages and improvements Taipan will have over previous generations of peculiar velocity surveys, and what we can expect from the complete Taipan peculiar velocity sample.

T85, 9:30–9:45 a.m. — Improved constraints on the growth rate of structure from modelling cross-correlation in the 6dF Galaxy Survey
Caitlin ADAMS, Swinburne University of Technology

While the Universe’s accelerating expansion is well established, its cause remains unknown. There are two promising explanations of the acceleration: dark energy (which assumes general relativity) and modified gravity. Changing the law of gravity on the largest scales will impact the formation of galaxies and galaxy clusters, resulting in a distribution of matter that differs from that predicted by general relativity. If we are to distinguish between these theories using observations, our measurements need to be incredibly precise. I will present a new maximum-likelihood approach that uses multiple observations at low redshift to better constrain the growth rate of structure, one of the key cosmological parameters for distinguishing between general relativity and modified gravity. Our approach takes advantage of the shared information between galaxy positions and velocities in the form of their cross-correlation. Applying this approach to the 6 degree Field Galaxy Survey, we find a 20% reduction in the uncertainty on the growth rate of structure when including the cross-correlation information. I will also discuss how new low-redshift surveys, such as Taipan, will further improve constraints on the growth rate in the coming years.

T86, 9:45–10:00 a.m. — Chasing the bright end of the z > 8 galaxy luminosity function: followup imaging of galaxies during reionisation with Spitzer IRAC
Stephanie BERNARD, University of Melbourne

Using the Wide Field Camera 3 on the Hubble Space Telescope, the frontier of galaxy studies at z ~ 9-11, only 500 million years after the Big Bang, is currently being explored. While the WFC3 is a powerful instrument that has opened up a rich new area of discovery, including the most high-redshift galaxy currently known, its view is still limited. By adding in imaging and spectroscopic data from other space-based and ground-based sources, such as Spitzer’s near-infrared IRAC camera, or the infrared MOSFIRE instrument on Keck, we can get a better view of the properties of these galaxies in the early Universe. I will present results from our Spitzer programme to followup over thirty z ~ 8-11 galaxy candidates from the Brightest of Reionising Galaxies (BoRG) survey, and the implications on the bright end of the UV galaxy luminosity function at these high redshifts.

T87, 10:00–10:15 a.m. — The SMBH-Galaxy Correlation for Milky Way and Andromeda-mass Progenitors Since z=2.5
Michael COWLEY, Macquarie University / Australian Astronomical Observatory

The growth of galaxy bulges is often associated with supermassive black holes (SMBHs), where local scaling relations, manifested in the $M-\sigma$ relation, have driven a wealth of research in the area of SMBH-galaxy co-evolution. However, what can be learned from efforts to track the co-evolution over different redshifts are often limited by selection bias in the underlying galaxy populations. Here I will discuss my efforts to address this by investigating the SMBH-galaxy correlations for the progenitors of $M^*$ galaxies, which include Milky Way-like and Andromeda-like galaxies. We track the relative growth rates between the progenitors and their SMBHs out to $z=2.5$ by performing X-ray stacking of the deepest Chandra data available, and by decomposing the infrared flux of the observed SEDs into their active galactic nuclei (AGN) and star-forming components. As the progenitors evolve, we find the rate at which they grow their black hole mass, relative to the growth of their stellar mass, to decline towards low-$z$. This result contrasts with previous studies, which tend to find little to no evolution with redshift. These studies often adopt X-ray or mass-limited galaxy samples, which include a broad mixture of galaxies with different evolutionary histories. Our use of progenitor-matched samples highlights the importance of carefully selecting progenitors when searching for evolutionary relationships between SMBHs and their hosts. Indeed, our finding of a decoupling between the relative growth rates between our progenitors and their central supermassive black holes casts doubts over a tight SMBH-galaxy relation through most of cosmic time.

Thu, 13 Jul, 10:15 a.m. to 10:30 a.m. Day ↑ | Top ↑

Conference Photo

Foyer, Crawford School of Public Policy

Please gather in the foyer for the conference photo!

Thu, 13 Jul, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Foyer, Crawford School of Public Policy

Thu, 13 Jul, 11:00 a.m. to 12:30 p.m. Day ↑ | Top ↑

Session 19 – Future Facilities

Molonglo Theatre

T88, 11:00–11:15 a.m. — Update on the Giant Magellan Telescope project
Matthew COLLESS, Australian National University

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

T89, 11:15–11:30 a.m. — An update on progress towards the Square Kilometre Array: engineering, science and governance
Sarah PEARCE, CSIRO Astronomy and Space Science

The international Square Kilometre Array Project (SKA) is working towards building the SKA1_Low telescope in Australia and SKA1_Mid in South Africa. Later this year, the SKA partners plan to sign a treaty that will establish an intergovernmental organisation, ready for construction of the telescopes. In parallel, the telescope designs are being finalised by international engineering consortia, with a strong focus on delivering transformational science instruments within the cost cap.  This talk will provide an update on SKA, with a focus on Australia’s role and contributions.

Jointly presented by:
David Luchetti, Australian SKA Director, Department of Industry and Science
Sarah Pearce, Deputy Director, CSIRO Astronomy and Space Science

T90, 11:30–11:45 a.m. — Science with Veloce - Australia's New Planet Foundry
Chris TINNEY, UNSW Sydney

The Veloce Rosso spectrograph and the VeloceCal laser comb will go into operation at the AAT early in 2018, opening up a new area of exoplanet detection for Australia. Delivering a capability to obtain sub-m/s Doppler velocity precision at wavelengths between 600 and 900nm, it will use multiple design innovations to target multiple science cases critical for exoplanetary science - the follow-up of new potentially habitable exoplanets discovered by the NASA TESS satellite; utilising variability measures from TESS to identify the best transiting systems to target for long-term studies of their system architectures (i.e. finding the subsequent planets that don't transit); and carrying out a new generation of exoplanetary surveys for the most stable-of-all host stars.

T91, 11:45 a.m. –12:00 p.m. — Imaging planet formation and stellar mass-loss with VAMPIRES
Barnaby NORRIS, University of Sydney

VAMPIRES is a newly commissioned high-angular resolution interferometric imager developed to directly image dusty planet-forming disks around young stars, and mass-loss regions around evolved stars. Developed at the University of Sydney, it is currently deployed at the 8 m Subaru telescope. VAMPIRES leverages aperture masking interferometry - providing diffraction-limited imaging despite seeing - in combination with fast-switching differential polarimetry, to directly image structure in the inner-most regions of these systems (using the polarisation properties of scattered starlight) at milliarcsecond scales. At the end of 2016 several major upgrades were made, including the ability to perform spectral-differential imaging, for example imaging the shocks from accreting proto-planets in H-alpha. The instrument has recently demonstrated observations of circumstellar environments with spatial resolution of ~10 mas. A description of the instrument and it’s latest exciting results will be presented.

T92, 12:00–12:15 p.m. — The Maunakea Spectroscopic Explorer
Doug SIMONS, Canada-France-Hawaii Telescope

The Maunakea Spectroscopic Explorer project will transform the CFHT 3.6m optical telescope into a 10m class dedicated multiobject spectroscopic facility, with an ability to simultaneously measure thousands of objects with a spectral resolution range spanning 2,000 to 20,000. The project is currently in design phase, with full science operations nominally resuming in 2025. Before completion in 2025, the project will also have transformed and expanded the partnership into one poised to tackle global themes in concert with the coming wide field surveys and the new Extremely Large Telescopes. MSE seeks to tackle basic science questions ranging from the origin of stars and stellar systems, Galaxy archaeology at early times, galaxy evolution across cosmic time, to cosmology and the nature of dark matter and dark energy. Given the highly successful Australian leadership of such major survey projects to date, and Australian expertise in delivering the instrumentation and technology to facilitate them, we are keen to engage the Australian community in the ongoing design and development of the MSE facility and the scientific projects it will conduct.

T93, 12:15–12:30 p.m. — High Energy Neutrino Astronomy with IceCube at the South Pole
Sally ROBERTSON, University of Adelaide

The IceCube neutrino observatory has been operating since 2011, and has observed a flux of high energy neutrinos from the distant Universe. In this talk we will present recent results from more than 6 years of data taking. Measurements of the properties of the flux, and dedicated searches for correlation with potential sources, e.g. AGN, GRBs, Blazars, Starburst galaxies and Fast Radio Bursts will be described. The proposed extension, IceCube-Gen2, to improve the detector capabilities, will also be outlined.

Thu, 13 Jul, 12:30 p.m. to 2:00 p.m. Day ↑ | Top ↑


Foyer, Crawford School of Public Policy

Speed Meet-A-Mentor

Molonglo Theatre

Thu, 13 Jul, 2:00 p.m. to 3:30 p.m. Day ↑ | Top ↑

Session 20 – Extreme Stars

Molonglo Theatre

T94, 2:00–2:15 p.m. — First detection of bifurcated blue straggler sequences in young globular clusters
Chengyuan LI, Macquarie University

Blue straggler stars (BSSs) are found in all types of stellar systems. In very rare cases, they are distributed into two well-separated branches in the color-magnitude diagram (CMD). This has been considered as an indication of the comparable importance of both BSS formation channels, stellar collisions and binary mass transfer. Using high-resolution Hubble Space Telescope observations, for the first time, we have detected an obvious bifurcated distribution in the CMD of BSSs in the 1.6 Gyr-old cluster, NGC 2173. Dynamical analysis carried out for this cluster shows that frequent stellar encounters are not responsible for the blue BSS branch, which would otherwise be understood as the result of direct stellar collisions. Therefore, the current study suggests that binary interactions, including mass transfer and final mergers, is the dominant channel for both the blue- and red-component BSSs. The blue sequence is likely due to merger events of high-mass-ratio binary systems resulting from exchange and hardening processes associated with the dynamical evolution of the cluster. We suggest that these dynamical processes happened about 250 Myr ago.

T96, 2:15–2:30 p.m. — Silicates in the embedded YSOs and the ISM revealed by Mid-IR spectroscopy
DO DUY Tho, UNSW Canberra

Utilising a range of instruments on 4-8 m telescopes we have observed a large sample of objects in the mid-infrared (8-13 µm) including a few OH/IR stars, several envelopes or disks of embedded Young Stellar Objects (YSOs) and diffuse sight-lines of the interstellar medium (ISM). In all objects we detect the typical absorption feature of amorphous silicates around 9.7 µm but clearly apparent in most objects is a second absorption band centred around 11.1 µm. Using a variety of approaches we confidently assign this feature to crystalline olivine, and probably the Mg-rich end-member forsterite. In some targets which have very high S/N we also detect features around 10.4 and 11.9 µm, confirming the forsterite identification. Modelling using a mixture of dust components and sizes shows that in most YSO and ISM cases the abundance of forsterite is around 1-2% however, several sources show much stronger features and thus higher abundances. This includes the BN Object in Orion, the archetypal cold molecular cloud source, the massive YSO AFGL 2591, as well as the supposed Herbig Be star AFGL 2789 (V645 Cyg). We propose that crystalline silicates are essentially ubiquitous in the embedded YSO phase. Especially intriguing is the first ever detection of crystalline silicate in the diffuse ISM, toward the Wolf-Rayet star AFGL 2104. We discuss the significance of our findings in the context of the cosmic dust life-cycle.

T98, 2:30–2:45 p.m. — Distributions of short-lived radio isotopes in the galactic disk
Yusuke FUJIMOTO, Australian National University

Understanding of the distributions of short-lived radio isotopes in the Galaxy is one of the important keys to understanding the possible birth environments of our Solar System in the galactic disc. Meteoritic evidence shows that the early Solar Nebula contained significant quantities of isotopes such as 26-Al and 60-Fe. These provided a significant source of ionisation, influencing the dynamics of the circumstellar disc. However, the origin of these isotopes is uncertain, since some, 60-Fe in particular, are produced primarily by supernovae. We describe new chemodynamical simulations of the Milky Way disc that combine high resolution hydrodynamics and chemical transport with stochastic star formation and element injection to follow the dynamics of short-lived radio isotopes on galactic scales. We present the results of these simulations and discuss a possible birth environment of our solar system within the galaxy.

T100, 2:45–3:00 p.m. — Optical and radio bubbles around rapidly-feeding stellar-mass black holes
Ryan URQUHART, International Centre for Radio Astronomy Research, Curtin University

Astronomers are moving towards a consensus that most ultraluminous X-ray sources (ULXs) are rapidly-accreting neutron stars or stellar-mass black holes. The extreme X-ray luminosities produced by these objects is therefore a result of super-Eddington accretion. The precise nature of such high mass accretion rates is still not fully understood and better constraints on the non-radiative energy output are required to study the inflow/outflow dynamic in these super-Eddington sources. Strong outflows from either disk winds or jets inject energy into the surrounding medium which manifest as 100-500 parsec optical and radio nebula. These ULX `bubbles' can be used to probe the energetics of the outflows and hence measure the mechanical power of the host ULX. We recently discovered two such examples of ULX bubbles, found in the Whirlpool Galaxy, M51. Here we present optical and radio observations of the two sources and use this to constrain the energetics of the outflows. Equipped with both the radiative (X-ray) and kinetic power components, we can start to build a better picture of the connection between inflow and outflow in these, and by extension other rapidly accreting systems.

T102, 3:00–3:15 p.m. — Measuring binary orbits with high-precision VLBI astrometry
James MILLER-JONES, International Centre for Radio Astronomy Research - Curtin University

Very Long Baseline Interferometry (VLBI) can provide extremely accurate measurements of the positions of radio-emitting sources, often limited only by systematic errors, to levels around a few tens of microarcseconds. For Galactic binary systems that comprise a radio-emitting object in orbit around a relatively high-mass star, this makes it possible to measure not only the proper motion and parallax of the binary, but also the size of the binary orbit, providing model-independent constraints on key system parameters such as the component masses and orbital inclination. In this talk I will present results from our recent astrometric campaigns on the high-mass X-ray binary system Cygnus X-1 and the gamma-ray binary PSR B1259-63. Our VLBA observations of Cygnus X-1 provide the first direct measurements of the orbit of a black hole. Our multi-year LBA program on PSR B1259-63 allows us to trace the motion of the neutron star in its 3.4-year orbit, which when combined with long-term pulsar timing data provides a complete solution for the orbital and astrometric parameters of the source, will provide constraints on the amount of power channeled into gamma rays, the gamma-ray emission mechanism, and the age and possible birthplace of the system.

T104, 3:15–3:30 p.m. — The first black hole – white dwarf binary discovered in the Galaxy
Vlad TUDOR, The International Centre for Radio Astronomy Research, Curtin University

The bright X-ray source X9 was discovered in the globular cluster 47 Tucanae in the early days of X-ray astronomy, and for decades it was assumed to be an accreting white dwarf. In 2015, however, radio emission was found to originate from this object, as bright as would rather be expected from the jets of a black hole. New X-ray data show oxygen emission and an extremely short orbital period (28 min) which reveal the donor likely is a C/O white dwarf. Consistent with this picture, optical spectroscopy with the Hubble Space Telescope, acquired in 2016, shows a featureless spectrum, in particular lacking the Hα line common among hydrogen-rich X-ray binaries. This identifies X9 as the first black hole – white dwarf binary candidate in the Galaxy. I will present these multi-wavelength observations of X9, and show a likely evolutionary sequence that likely lead to its formation.

Session 21 – Galaxy Properties and Evolution

Barton Theatre

T95, 2:00–2:15 p.m. — Calibrations of radio continuum, mid-infrared and UV star formation rate indicators
Michael BROWN, Monash University

We present new calibrations of star formation rate indicators at 150 MHz, 1.4 GHz, mid-infrared and UV wavelengths. Our calibrations utilise matched aperture photometry and spectrophotometry of 64 nearby galaxies, and we address several sources of systematic and random error, including photometric calibration, scattered light, filter curve errors and galaxy distances. Our mid-infrared calibrations indicate that the star formation rates of low metallicity dwarf galaxies may have been underestimated by the prior literature. We present the first direct calibration of 150 MHz as a star formation rate indicator, and find it measures star formation rates with an accuracy (0.24 dex) comparable to that of 1.4 GHz and 24 micron measurements. Work is underway to extend these calibrations into the far-infrared and the JWST MIRI filter-set, and preliminary results will be presented.

T97, 2:15–2:30 p.m. — The drivers of Stellar Population in Early-Type Galaxies
Tania BARONE, Australian National University

The well-established correlations between the mass $M_*$ of a galaxy and the properties of its stars are considered to be evidence for mass being the primary driver for the evolution of the stellar population. However, we find that $g-i$ colour and stellar metallicity $[Z/H]$ correlate more strongly with gravitational potential $\Phi_*$ than with mass, while stellar population age and star formation duration $[\alpha/Fe]$ correlate best with surface density $\Sigma_*$. Specifically, for early-type galaxies from the SAMI integral field spectroscopy survey, we find that, compared to correlations with $M_*$, the $g-i$ colour--$\Phi_*$, $[Z/H]$--$\Phi_*$, age--$\Sigma_*$ and $[\alpha/Fe]$--$\Sigma_*$ relations show smaller scatter and less residual trend with galaxy size. From these results we draw three main conclusions: (1)~the gravitational potential $\Phi_*$ is the primary driver for stellar metallicity $[Z/H]$, regulating the escape velocity of enriched gas; (2)~the age--$\Sigma_*$ and $[\alpha/Fe]$--$\Sigma_*$ relations result from the specific star-formation rate in the blue cloud being driven by surface density $\Sigma_*$, consistent with the empirical Kennicutt-Schmidt law; and (3)~the colour--$\Phi_*$ diagram is a more powerful tool for characterizing galaxies than the conventional colour--$M_*$ diagram.

T99, 2:30–2:45 p.m. — Galaxies Growing Old: the Transition to Quiescence at $3\times10^{10} {\rm M}_\odot$
Philip TAYLOR, Australian National Univerity

I will present results of a cosmological simulation that includes star formation and feedback, chemical evolution, and supermassive black holes. By fitting a simple function of stellar mass, gas mass, black hole mass, and environment to the star formation rate (SFR) of galaxies, I will show that SFR is primarily determined by the gas content of a galaxy, and is much less dependent on the stellar mass than suggested by the star forming main sequence. I will also show that feedback from black holes becomes important once they have grown to $\sim2\times10^7{\rm M}_\odot$, corresponding to a stellar mass of $\sim3\times10^{10}{\rm M}_\odot$, in agreement with observations (eg, Kauffmann 2003). Furthermore, this model is able to reproduce well the SFR inferred from observations of galaxies matched between the GAMA and ALFALFA surveys.

T101, 2:45–3:00 p.m. — Do Massive Galaxies Dance in Crowds?
Sarah BROUGH, University of New South Wales

The bulk movement of the stars in galaxies tells us about their past lives. Simulations show that galaxies form with their stars rotating fast, but that rotation slows over time due to galaxy mergers. Observed samples to-date have been too small to say whether the slow down of rotation is caused by increasing galaxy mass or by the external effects of galaxy environment. Recent results from the significantly larger SAMI Galaxy Survey show that rotation depends only on galaxy mass, but since galaxy mass depends on environment: massive galaxies don’t dance in crowds

T103, 3:00–3:15 p.m. — Cosmic Clocks: the Radius Velocity Reltionship of Disc Galaxies
Gerhardt MEURER, International Centre for Radio Astronomy Research, University of Western Australia

We show that the outskirts of disc galaxies obey a linear radius (R) versus rotational velocity (V) relationship. This means they behave like clocks: they have the same orbital time of 1 Gyr at the outer edge of their discs. The relationship is valid over the full range for which we have data - a factor of 30 from dwarf galaxies with R ~ 1 kpc and V ~ 10 km/s to giant spirals with R = 30 kpc and V = 300 km/s with an intrinsic scatter smaller than 40%. A linear RV relationship is expected for Cold Dark Matter (CDM) dominated halos. The mean density within the outer disc radius is 2e-3 Msun/pc^3, requiring that the baryonic component of disc galaxies to have collapsed by a factor of ~37. While the CDM paradigm provides a natural frame-work for understanding RV relationship, it would imply that discs grow outward through accretion, while various observations indicate outer discs are fairly evolved. Various ideas on what set the maximum disc radius are reviewed in the light of our result.

T105, 3:15–3:30 p.m. — Spatially-resolved measurements of nebular parameters in AGN including arbitrary narrow line region (NLR) - HII region mixing
Adam Douglas THOMAS, The Australian National University

We present a code providing a new and general way to compare measured emission-line fluxes with photoionisation model grids, NebulaBayes, and demonstrate applications of the code.  Optical IFU data from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) is used in a case study.  We combine HII-region and AGN narrow line region (NLR) model grids in order to constrain nebular parameters for spectra which lie along the "mixing sequence" between HII-regions and NLRs on optical diagnostic diagrams.  The results show gradients in pressure and ionisation prameter along the extended narrow-line region of the example galaxy.  Routine measurements of nebular parameters using spectra with arbitrary mixing between NLR and HII regions hold promise for expanding our understanding of AGN feedback on the host galaxy.

Thu, 13 Jul, 3:30 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

Foyer, Crawford School of Public Policy

Thu, 13 Jul, 4:00 p.m. to 5:00 p.m. Day ↑ | Top ↑

Session 22 – Exoplanets

Molonglo Theatre

T106, 4:00–4:15 p.m. — Searching for Young Exoplanets with High-Contrast Imaging in the Near Infrared
Alexander WALLACE, Australian National University

Direct imaging of exoplanets is limited by the optics of the telescope which need to be removed by deconvolution or subtraction of point spread functions. In this project, existing methods of image analysis are tested with a large sample of young stars imaged by Keck, especially in the Taurus association, to search for companions. I am improving on these analysis methods with novel forward modelling methods to help establish new sensitivity limits for planet detection and, in the event of any clear detections, improve our understanding of planet formation.

T108, 4:15–4:30 p.m. — Diffraction limited and high contrast imaging of circumstellar environments at the AAT
Tiphaine LAGADEC, University of Sydney

With many thousands exoplanets discovered one of the important next steps in astronomy is to be able to characterise them. This presents a great challenge and calls for new observational capabilities with both high angular resolution and extreme high contrast in order to efficiently separate the bright light of a host star to that of a faint companion. Glint South is an instrument that uses photonics technology to perform nulling interferometry. The light of a star is cancelled out by means of destructive interference in a tiny photonics chip. One of the challenges is the star light injection into the chip. This is done by a unique active system that optimises the injection and provide low order correction for the atmospheric turbulence. We are reporting on the latest progresses following several tests on the Anglo Australian Telescope.

T110, 4:30–4:45 p.m. — Mapping young suns and searching for their exoplanets
Belinda NICHOLSON, University of Southern Queensland

Young solar-type stars provide insights into the rapidly rotating young Sun’s intense dynamo-powered magnetic activity and wind. At the same time their extreme activity presents challenges for detecting exoplanets. The techniques of Doppler Imaging (DI) and Zeeman Doppler Imaging (ZDI) are powerful tools for examining young stars and planetary systems, allowing us to reconstruct the surface brightness and large scale magnetic fields of these stars from high-resolution spectropolarimetric data. The information gained about a star’s surface brightness inhomogeneities allows us to characterise the activity-related jitter in radial velocity (RV) measurements, and then remove it to explore any underlying RV signals due to the presence of young exoplanets. We present the results of DI, RV and ZDI analysis for a young (~10Myr), non-accreting weak-line T Tauri star as part of the MaTYSSE collaboration, and the results of ongoing work to simulate the star’s wind using the ZDI information in a 3D MHD wind model.

T112, 4:45–5:00 p.m. — TRAPPIST-1 and other resonant chain planetary systems
Rosemary MARDLING, Monash University

Resonant chains are a beautiful example of Nature’s ability to create highly complex structures in a thermodynamically favourable environment. The best known example of such a celestial molecule held together by gravity is Jupiter’s Laplace resonance for which the orbital periods of Io, Europa and Ganymede are such that 1/P_I-3/P_E+2/P_G< 10^-9 deg/day. The TRAPPIST-1 systems consists of 7 terrestrial planets involving 5 Laplace resonances. Such a system is rich with dynamical information about the planet masses, stability properties, dissipative properties of the planets and the disk from which they formed. In this talk I will discuss how transit timing variations can be used together with our theoretical understanding to deduce these and other properties.

Session 23 – Molecules in the Universe

Barton Theatre

T107, 4:00–4:15 p.m. — Gas clumps near hot stars cause extreme radio scattering
Artem TUNTSOV, Manly Astrophysics

We demonstrate that extreme radio scintillation is associated with hot stars in the solar neighbourhood. The ionised gas responsible for the scattering forms skin of tiny molecular clumps found at distances up to 2 pc from the host star, and there should be around 100,000 such clouds per star. The circumstellar plasma structures that we infer are similar to the cometary knots seen in planetary nebulae. Our analysis suggests that molecular clumps are ubiquitous circumstellar features, unrelated to the evolutionary state of the star. The total mass in such clumps is comparable to the stellar mass.

T109, 4:15–4:30 p.m. — Interpreting the results of large, multi-molecular-line datasets of the molecular ISM
Maria CUNNINGHAM, University of New South Wales

In the last decade, the development of wide-bandwidth receivers and fast wide-field mapping has let to the collection of far more data then can possibly be processed and analysed manually. In this presentation we describe how automated data processing techniques, such as principal component analysis, filament finding algorithms and probability density function analysis can be used to interpret these large multi-line datasets. We discuss how these techniques have been used to analyse the G333 and Vela C molecular clouds, and determine which molecules respectively trace the turbulent and gravitationally bound components of the interstellar medium. We also show how the comparison of subsets of molecules, for example CS, N2H+, HCO+ and C2H can be used to highlight star forming regions at different stages of development in these large datasets.

T111, 4:30–4:45 p.m. — Searching for Molecular Building Blocks at Low Frequencies
Chenoa TREMBLAY, ICRAR-Curtin University

Over the last 50 years, radio astronomy has played an important role in the discovery of molecules within our Galaxy. In the 1980s, pushing molecular searches towards infrared and optical frequencies was productive due to radio interference at low GHz frequencies. However, with the discovery of the first chiral molecule at 12 GHz last year, there has been a resurgence of molecular searches at lower frequencies. This work aims to detect more low-frequency molecular transitions using state-of-the-art instruments at ~100MHz to search for the large chain molecular building blocks for life and base transitions of simple molecules. We have successfully conducted a spectral-line survey of 400 square degrees over the Galactic plane, where we have tentatively discovered molecular transitions toward evolved stars using the Murchison Widefield Array. We will present our low-frequency molecular detections, discuss their implications and present our future plans in this research space.

T113, 4:45–5:00 p.m. — Abiotic Chemical Disequilibria In Exo-Earth Atmospheres: Improving Future Biosignature Detections By Identifying False Positives
Sarah MCINTYRE, Australian National University

The discovery and characterization of exoplanets has the potential to lead to the identification of life beyond Earth. It has been hypothesised that life can be inferred by the presence of atmospheric biomarkers – biologically produced gases that accumulate in sufficient quantities to result in detectable atmospheric chemical disequilibrium (Krissansen-Totton et al., 2016; Seager et al., 2016). To determine whether exoplanets like Proxima b and the TRAPPIST-1 system are likely to support life, we need to extend our exploration into the potential biological characteristics of their atmospheres. It is important to acknowledge that extraterrestrial life, provided it exists, could be quite unlike the forms of life we are familiar with (Sagan, 1993). For this reason, chemical disequilibrium as a biosignature is appealing because it is a generalized life-detection metric which relies solely on the notion that distinct metabolisms in a biosphere produce waste gases that, with sufficient fluxes, will alter atmospheric composition and result in disequilibrium (Krissansen-Totton et al., 2016). Unfortunately, the gases expected to be produced in abundance by life are ones that are also rife with false positives. The worth of a biosignature is not only determined by the probability of life creating it, but equally by the improbability of non-biological (abiotic) processes producing it (Des Marais, 2013). If all abiotic abundances (O2, N2, N2O, CO2, H2O, O3, CO, CO2, CH4, H2S etc…) can be identified, quantified and eliminated from the spectroscopic data, we will be one step closer to potentially detecting the life on another planet. References: Des Marais, D.J., 2013. Planetary Climate and the Search for Life. Comparative Climatology of Terrestrial Planets, pp.583-601. Krissansen-Totton, J., Bergsman, D.S. and Catling, D.C., 2016. On detecting biospheres from chemical thermodynamic disequilibrium in planetary atmospheres. Astrobiology, 16(1), pp.39-67. Seager, S., Bains, W. and Petkowski, J.J., 2016. Toward a List of Molecules as Potential Biosignature Gases for the Search for Life on Exoplanets and Applications to Terrestrial Biochemistry. Astrobiology, 16(6), pp.465-485. Sagan, C., Thompson, W.R., Carlson, R., Gurnett, D. and Hord, C., 1993. A search for life on Earth from the Galileo spacecraft. Nature, 365(6448), p.715.

Thu, 13 Jul, 6:00 p.m. to 10:45 p.m. Day ↑ | Top ↑

Transportation to Old Parliament House

Departs: Crawford Building

ASA Conference Dinner

Registration required

6:30 p.m. – 10:30 p.m. @ Old Parliament House

This event is sponsored by the ANU Research School of Astronomy and Astrophysics.

The ASA Conference Dinner with be held on the night of Thursday, 13 July at Old Parliament House. Transport to the dinner from the conference venue will be provided.

The registration cost for this event is included ...

More info →

Transportation to ANU Campus

Departs: Old Parliament House

Fri, 14 Jul

9:30–10:30 a.m. | 10:30–11:00 a.m. | 11:00 a.m. –12:15 p.m. | 12:15–1:30 p.m. | 1:30–3:15 p.m. | 3:15–4:00 p.m. | 4:00–8:00 p.m.

Fri, 14 Jul, 9:30 a.m. to 10:30 a.m. Day ↑ | Top ↑

Session 24 – From the Big Bang to Us

Molonglo Theatre

T114, 9:30–9:45 a.m. — Cracks in LCDM: real or imagined?
Christian REICHARDT, The University of Melbourne

With the superb measurements of the cosmic microwave background by the Planck satellite came a number of low-significance hints of tension in the standard LCDM cosmological model. These include tensions between different measurements of the Hubble constant, the growth of large-scale structure ($\sigma_8$), and perhaps most surprisingly, even the CMB power spectra as measured by different experiments. I will discuss the observed tension between the CMB power spectra from the South Pole Telescope and the Planck satellite, and present results from a new analysis testing for the sources of the differences. Are the differences attributable to sample variance, to instrumental systematics, or to a breakdown in LCDM model?

T115, 9:45–10:00 a.m. — Measuring the mass of galaxy clusters with cosmic microwave background lensing
Sanjaykumar PATIL, University of Melbourne

Galaxy clusters are the largest gravitationally bound objects in the Universe and provide crucial insight to the standard model of Cosmology. Their abundance as a function of mass and redshift is highly sensitive to cosmological parameters such as the amplitude of matter fluctuations and the dark energy equation of state. Though galaxy clusters are powerful probes of cosmology, they are currently limited by a ~15% mass uncertainty. Future surveys like LSST and eROSITA will provide even larger samples of galaxy clusters; our ability to fully realise the potential of these samples depends on better mass estimates. Gravitational lensing is widely considered the gold standard in mass estimation. In this talk I will present a method to extract the lensing signal from the CMB data. We predict cluster mass uncertainties will be improved to 3-6% for SPT-3G, AdvACT, and Simons Array experiments and to less than 1% for CMB-S4 experiment.

T116, 10:00–10:15 a.m. — Resolving the Disk-Halo Degeneracy
Suryashree ANIYAN, Australian National University

The decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo remains uncertain and depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion of stars in the disk and its scale height, the disk surface density and hence the M/L can be estimated. Earlier works have used integrated light and other tracers (like planetary nebulae) to conclude that galaxy disks are submaximal. However, I aim to address an important conceptual problem that has previously not been included in the velocity dispersion estimates. Measuring the surface density of the disk requires a velocity dispersion and a disk scale height but they must be for the same population of the tracers. Disks of spirals contain tracers of all ages. The younger stars (ages < 2 Gyr) have a relatively small scale height and velocity dispersion, compared to the older, kinematically hotter stars. Since it is not possible to measure the scale height directly in face-on disks, we need to estimate it statistically using I-band and near-IR photometric data for edge-on galaxies; these estimates are weighted towards the scaleheight of the old disk. The spectra of the integrated light of the disk, which we use to measure the vertical velocity dispersion, come from the luminosity-weighted stellar population of the disk and contain a considerable contribution from the kinematically colder, younger disk population (see Aniyan et al. 2016). Failing to separate out this younger component, will lead to underestimating the velocity dispersion. The surface density of the disk is therefore underestimated, and a maximal disk will appear to be submaximal. I present the first results from the analysis of a sample of nearby face-on spiral galaxies to demonstrate the presence of a young, kinematically colder component and its effect on the disk-halo decomposition in these galaxies.

T117, 10:15–10:30 a.m. — Revolutions in polarisation: Leveraging next-generation radio telescopes and Faraday rotation to unveil the magnetised structure of radio galaxies

The linearly polarised emission from cosmic radio sources can be used as a probe of their own internal magneto-ionised structure, by studying the subtle ways in which Faraday rotation can imprint frequency-dependent structure on this emission. For many years, Faraday rotation studies were largely concerned with the calculation and analysis of 'rotation measures' (RMs) --- the gradient of a linear fit to the polarisation angle vs. the square of the observing wavelength. However, modern observations have revealed the existence of a wealth of complicated frequency-dependent changes in polarisation that are not encapsulated by RMs, but which provide powerful new insights into the magnetoionic structure of radio sources. In this talk, I will discuss the results of recent experiments designed to observe and characterise these complex polarisation behaviours in cosmic radio sources. After emphasising that these behaviours are detected in a substantial proportion of radio sources, I will discuss several recent and novel results in this area, including our study of the magnetised structure of Fornax A, and the ability to reveal changes in the parsec-scale magneto-ionised structure of AGN jets through time-resolved broadband polarimetry. I will conclude by discussing how ASKAP and the SKA can exploit this information to provide a powerful new probe of magnetised structure in different cosmic environments.

Fri, 14 Jul, 10:30 a.m. to 11:00 a.m. Day ↑ | Top ↑

Morning Tea

Foyer, Crawford School of Public Policy

Fri, 14 Jul, 11:00 a.m. to 12:15 p.m. Day ↑ | Top ↑

Session 25 – From the Big Bang to Us (cont.)

Molonglo Theatre

T118, 11:00–11:30 a.m. — The many muses of radio variability from the ATESE survey (Louise Webster Prize talk)
Keith BANNISTER, Australia Telescope National Facility

⇒ This talk is by the winner of the Louise Webster Prize

The Australia Telescope Extreme Scattering Events (ATESE) survey has been running on the Australia Telescope Compact Array for the last 3 years. It has uncovered remarkable diversity in the light curves of extragalactic radio sources, including extreme scattering events, intraday variability, and flares from active galactic nuclei. This variability has inspired surprising insights into tiny structures in the interstellar medium, the size and shape of the emission region around a supermassive black hole, and the nature of molecular gas around hot stars. I will describe the survey, its main achievements, and public data release.

T119, 11:30–11:45 a.m. — Mid-Infrared Observations with CanariCam on the Gran Telescopio Canarias
Christopher WRIGHT, University of New South Wales, Canberra

CanariCam is the facility mid-infrared camera, spectrometer and polarimeter on the 10.4 m Gran Telescopio Canarias. We will present results from CanariCam in all its operational modes, spanning multi-epoch spectroscopy of Type 1a SN 2014J in M82 (Telesco et al. 2015), imaging polarimetry of star forming regions and protoplanetary disks, and spectropolarimetry of embedded young stellar objects and Herbig stars. As CanariCam is the first ever dual-beam mid-IR polarimeter, and the only such instrument to have made scheduled observations on an 8-10 m class telescope, significant advances in the fields of magnetism in star and planet formation, as well as the cosmic dust life-cycle, have already been achieved. An example includes the first demonstration of polarisation 'tomography' of a star formation region (K3-50, Barnes et al. 2015), which allowed mapping of the magnetic field within both the outer (cold) envelope and the inner (warm) region. Others are the first detection of the magnetic field within a protoplanetary disk (AB Aur, Li et al. 2016) and most recently the first detection of polarisation from polycyclic aromatic hydrocarbons (Zhang et al. 2017, submitted). These and several other results will be summarised.

T120, 11:45 a.m. –12:00 p.m. — Shaping the circumgalactic medium through radio-loud AGN interactions on kpc scales
Julie BANFIELD, Australian National University

Though the radio-mode feedback from active galactic nuclei (AGN) has been identified as a likely source of feedback in high mass galaxy formation, few such systems have been directly observed. As the radio-loud AGN jets break through the host galaxy, they can help to remove gas from the system or heat the gas up, thus helping to prevent or quench star formation. At the same time the radio-loud AGN jets can affect the circumgalactic medium and the nearby galaxies as they expand away from the host galaxy. Radio-loud AGN can be used to study AGN feedback due to the amount of energy the radio jets deposit in their surrounding environment. I present the recent results of a population of radio-loud AGN with their host galaxies revealing strong [OIII]5007 and optical morphologies more akin to late-type disks rather than early-type spheroids. Additionally, 50 per cent of these host galaxies of the radio-loud AGN show clear evidence of Ha outflows driven-off the galaxy disk by the AGN activity. The radio structure of the AGN show a number of morphologies including x-shaped radio emission where the radio-loud jets are interacting with the gas reservoirs of the cirumgalactic medium at kpc scales. I will present evidence that these radio-loud AGN may be the cousins of the radio-jet and molecular gas interaction found in Minkowski’s Object, 3C 285, 4C 41.17, and Centaurus A.

T121, 12:00–12:15 p.m. — The survival of cold gas in the Circumgalactic Medium

Several lines of evidence have shown that low-redshift galaxies are surrounded by extended halos of multiphase gas, the so-called ‘circumgalactic medium’, with a significant component of cold and photoionized gas (T < 10^5 K). Through high-resolution hydrodynamical simulations, we studied the physical phenomena that drive the interaction and mixing between the different gas phases and, in particular, which conditions allow the survival of clouds of cold gas in the hot and low-density galactic coronae. Our simulations include radiative cooling, thermal conduction and photoionizing heating. The main result is that the survival time of the clouds strongly depends on their mass: clouds with mass larger than 5x10^4 solar masses lose cold gas during their trajectory but at very low rates. They can survive the journey through the galactic corona for several hundreds of Myr, potentially providing a significant amount of cold gas accretion in star-forming galaxies and explaining how they keep getting gas from the surrounding environment to sustain their star formation at the current observed rates.

Fri, 14 Jul, 12:15 p.m. to 1:30 p.m. Day ↑ | Top ↑


Foyer, Crawford School of Public Policy

ECR Chapter Meeting – Sponsored by Sydney & Macquarie Universities

Molonglo Theatre

Fri, 14 Jul, 1:30 p.m. to 3:15 p.m. Day ↑ | Top ↑

Session 26 – Gravitational Waves and Black Holes

Molonglo Theatre

T122, 1:30–1:45 p.m. — Differentiating between black hole populations from GW observations of merger events
Letizia SAMMUT, Monash University

Following the first Advanced LIGO detection of two merging black holes, several studies investigated the possibility that the GW150914 binary system was of primordial origin and could provide evidence of black holes forming some part of dark matter. It has been shown that the merger rate redshift profile differs between models of binary black holes from stellar and primordial populations. We investigate the possibility of distinguishing between the two populations given redshift measurements of merger events from current and future GW detectors. We quantify what fraction of events would need to originate from a primordial population in order to differentiate between the progenitor populations, given the horizon distance of our detectors. We also investigate how far in redshift we would need to be sensitive in order for a single event to unarguably disfavour events from the stellar population.

T123, 1:45–2:00 p.m. — Searching for the first EM counterparts to gravitational waves in aLIGO second science run
David Martin COWARD, University of Western Australia

Advanced LIGO has been searching for gravitational wave (GW) signals in the second science run. The most promising signals to date have been binary black hole mergers. In the near future aLIGO will be joined by Virgo to search for other compact binary mergers: black-hole neutron star and binary neutron star mergers. The latter are possible associated with gamma ray bursts. We provide an overview of the process of coincident electromagnetic and gravitational wave searched for these sources. We describe how promising GW candidates are selected for possible distribution to a select group of astronomers to search for electromagnetic counterparts. We discuss the future of this new era of discovery in the context of contemporary astronomy.

T124, 2:00–2:15 p.m. — Gravitational-wave spectroscopy and tests of the no-hair theorem
Paul LASKY, Monash University

General relativity's no-hair theorem states that isolated astrophysical black holes can be described by only two numbers: mass and spin. Testing the no-hair theorem has been a longstanding goal of gravitational-wave astronomy. The recent LIGO detections of gravitational waves from black hole mergers would seem to make such tests imminent. I will discuss the prospects for such tests with ensembles of gravitational-wave events, including some interesting effects that can be seen as the sensitivity of gravitational-wave detectors improves.

T125, 2:15–2:30 p.m. — AGN Reverberation Mapping with OzDES
Janie HOORMANN, University of Queensland

Active galactic nuclei (AGN) reverberation mapping is a technique that measures time delays in the emission from the immediate surroundings of a galaxy's central supermassive black hole. This time delay can then be used to determine the geometry of these regions which are too small to image directly. As part of the Australian Dark Energy Survey (OzDES), 771 AGN with z < 4 are being regularly monitored. The current state-of-the-art sample only includes ~65 AGN out to z < 0.8. The time lag measurements that will be inferred from the monitoring can then be used to determine the mass of the central black hole with which we plan to measure how galactic supermassive black holes have evolved over the last 12 billion years. In addition, we will be able to extend the radius-luminosity relationship to higher redshifts using measurements of the MgII and CIV emission lines. OzDES has completed its fourth year of observations and we will present the current results of the reverberation mapping campaign.

T126, 2:30–2:45 p.m. — Fundamentally confused? Nature, nurture and radio galaxy scaling relations.
Stas SHABALA, University of Tasmania

The so-called Fundamental Plane (FP) of black hole activity relates observable jet properties (measured via radio synchrotron emission) to those of the black hole (namely mass and dimensionless accretion rate). The FP correlations hold for supermassive and Galactic black holes, and provide important insights into accretion and outflow physics. Focusing on scaling relations in supermassive black holes, I use SDSS, FIRST and NVSS data together with dynamical models of radio AGN to show that much of the observed low-redshift FP is due to two mechanisms: (1) existence of different scaling relations for high and low accretion rate states; and (2) the role of large-scale (tens to hundreds of kpc) environment in determining both the accretion mode and strength of observed lobe synchrotron emission. In this picture, the black hole mass dependence is best understood as a proxy for environment. A specific prediction of the models is that current surveys systematically underestimate radio emission associated with AGN in poor environments, due to insufficient surface brightness sensitivity. The observed slope and normalisation of the FP therefore should depend on both the sample demographics and observing strategy. Data from the ongoing GAMA Legacy ATCA Southern Survey (GLASS) will test these predictions.

T127, 2:45–3:00 p.m. — Updating the (Supermassive Black Hole Mass) -- (Spiral Arm Pitch Angle) Correlation: a Strong Correlation for Galaxies with Pseudobulges
Benjamin DAVIS, Swinburne University of Technology

We have conducted an image analysis of the (current) full sample of 44 spiral galaxies with directly measured supermassive black hole (SMBH) masses, $M_{\rm BH}$, to determine the galaxies' logarithmic spiral arm pitch angle, $\phi$. For predicting black hole masses, we have derived the relation: $\log({M_{\rm BH}/M_{\sun}}) = (6.99\pm0.07) - (0.172\pm0.019)\left[|\phi|-15\degr\right]$. The raw scatter associated with this relation is 0.40 dex with an intrinsic scatter of $0.31\pm0.07$ dex in the $\log{M_{\rm BH}}$ direction. The $M_{\rm BH}$--$\phi$ relation is additionally capable of estimating black hole masses in bulge-less spiral galaxies, and therefore has great promise for predicting which galaxies may harbour intermediate-mass black holes (IMBHs, $M_{\rm BH}<10^5$ $M_{\sun}$) and exploring the issue of seed mass progenitors to SMBHs. Extrapolating the current relation, we predict that galaxies with spiral arm pitch angle $|\phi| \geq 26.5\degr$ should have IMBHs. As such, the $M_{\rm BH}$--$\phi$ relation could play an important role in investigating the possible evolutionary link of seed mass progenitors to SMBHs. We find no statistical difference between the $M_{\rm BH}$--$\phi$ relation for galaxies with barred and unbarred morphologies. By definition, the existence of an $M_{\rm BH}$--$\phi$ relation demands that the SMBH mass must correlate with the galaxy disks in some manner. Furthermore, with the majority of our sample (37 of 44) classified as having pseudobulge morphologies, we have revealed that the SMBH mass correlates with the large scale spiral pattern and thus the disks of galaxies hosting pseudobulges.

T128, 3:00–3:15 p.m. — Using Microlensing to Probe Strong Gravity Near Supermassive Black Holes
George CHARTAS, College of Charleston

We present a promising new technique (g-distribution method) for measuring the innermost stable circular orbit (ISCO), the inclination angle ($i$), and the spin of a supermassive black hole. The g-distribution method involves measurements of the distribution of the energy shifts of the relativistic iron line emitted from the accretion disk of a supermassive black hole that is microlensed by stars in a foreground galaxy and a comparison of the measured g-distribution with microlensing caustic simulations. The method has been applied to the gravitationally lensed quasars RX~J1131$-$1231 ($z_{\rm s}$ = 0.658, $z_{\rm l}$ = 0.295), QJ~0158$-$4325 ($z_{\rm s}$ = 1.29, $z_{\rm l}$ = 0.317), and SDSS~1004$+$4112 ($z_{\rm s}$ = 1.73, $z_{\rm l}$ = 0.68). For RX~J1131$-$1231 our initial results indicate an ISCO radius of $<$ 8.5 gravitational radii, a spin parameter of $a$ $>$ 0.8 and and $i > 55$ degrees. Further monitoring of lensed quasars will provide tighter constraints on their inclination angles, ISCO radii, and spins. We finally compare numerical simulations of microlensing of the Fe Ka line to our observations.

Fri, 14 Jul, 3:15 p.m. to 4:00 p.m. Day ↑ | Top ↑

Afternoon Tea

Foyer, Crawford School of Public Policy

Fri, 14 Jul, 4:00 p.m. to 8:00 p.m. Day ↑ | Top ↑

Introduction To Machine Learning

Registration required

4:00 p.m. – 8:00 p.m. @ Griffin Seminar Room

Run by Astronomy Data and Computing Services (ADACS), this workshop will introduce machine learning concepts, where possible showing astronomy examples.
The introduction is followed by a hands-on session on designing basic machine learning workflows for supervised and unsupervised learning approaches, classification and regression methods and model tuning.
There ...

More info →