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Colloquia Series

For more information on colloquia at the Centre for Astrophysics and Supercomputing please contact Dr. Simon Stevenson ()

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2022 Colloquia

Thursday Jun 23, 10:30
Sree Oh (ANU)
Colloquium: Kinematic scaling relations for galaxy bulges, disks, and ionized gas from 3D spectroscopy
Galaxies show a wide range of kinematic properties according to galaxy types. We aim to quantitatively understand the intrinsic distribution of bulge and disk kinematics, and how two components describe the overall distribution of stellar kinematics of galaxies. The spatially-resolved rotation velocity and the velocity dispersion of bulge and disk components have been simultaneously estimated for the SAMI 3D spectroscopy data using the penalised pixel fitting method. Kinematic scaling relations demonstrate that the galaxy stellar mass scales with kinematics for both bulge and disk components of all galaxy types, which suggests kinematics of two components are less dependent on galaxy populations and largely determined by the mass. We quantitatively show that the bulge and disk components are kinematically distinct: the two components show scaling relations with similar slopes, but different intercepts; the spin parameter λR indicates bulges (disks) are pressure(rotation)-dominated systems. Our findings suggest that the relative contributions of bulge and disk components explain, at least to first order, the complex kinematic behaviour of galaxies according to galaxy type. On the other hand, kinematics of ionized gas are significantly impacted by power sources (e.g. star formation, AGN, and old stars), unlike stellar kinematics. For star-forming galaxies, the stellar velocity dispersion tends to be larger than the gas velocity dispersion, suggesting that stars are, in general, dynamically hotter than the ionised gas (asymmetric drift). However, AGN show gas velocity dispersions comparable to stellar ones, implying their gas kinematics have been dynamically heated by AGN activities (e.g. outflows).

Meeting ID: 817 2182 3000
Meeting PC: 084183
Thursday Jun 16, 10:30
Ben McAllister (Swinburne)
Colloquium: CAS Colloquium
Tuesday Jun 14, 10:30
Burak Dogruel (CAS)
Student Review: DTR: Burak Dogruel
Thursday Jun 9, 10:30
Stefania Barsanti (ANU)
Colloquium: TBA
Thursday May 26, 10:30
Robert Mosoghiu (Swinburne)
Colloquium: Cosmological simulations and the search for dark matter
Cosmological simulations have become an essential tool for testing structure formation theories. The advances in both observational and computational techniques over the years ultimately have allowed us to pick LCDM as the standard model of cosmology. Nevertheless, cosmological simulations highlight the intrinsic degeneracy between alternative dark matter models and the baryonic prescriptions we use in LCDM simulations. In order to break this degeneracy, we have to consider a series of challenges to our analysis and design our tests accordingly. In this talk I will present some of my previous research into galaxy formation problems within LCDM, and the outline of the simulating alternative dark matter models collaboration I recently started.
Thursday May 19, 10:30
Sam Vaughan (University of Sydney)
Colloquium: Scanning galactic barcodes: The stellar populations of nearby galaxies from spatially resolved spectroscopy
Studying absorption and emission lines in the spectra of nearby galaxies is an invaluable tool for learning about their stars. Whilst spectroscopy has a long history, the arrival of large integral field unit surveys in the past few decades has allowed astronomers to obtain exquisitely detailed ‘three dimensional’ data for thousands of nearby galaxies for the first time. I will give an overview of my research into the stellar populations of galaxies, including an investigation of the low-mass end of the initial mass function, whilst also discussing the prospects for studying stellar populations in the coming years.
Thursday May 5, 13:00
Jacob Askew ()
Student Review: Confirmation of Candidature Review
Tuesday May 3, 10:30
Hilton Lewis (Keck Observatory)
Colloquium: The W.M. Keck Observatory
The twin Keck 10m telescopes on Maunakea, Hawaii are amongst the most productive facilities for ground-based optical/IR astronomy in the world, with the highest scientific impact in ground-based OIR research. In their over 25 years of operation, discoveries made using the Keck telescopes have resulted in major advances in astronomy, and have played a leading role in the awarding of two Nobel prizes. Over the next decade, substantial new research facilities will come online worldwide and in space, and the Keck Observatory is adapting to continue to be a forefront research tool for the most challenging astronomy questions.

This talk will discuss the current status of the Keck Observatory operations and instrumentation, new instrumentation and capabilities currently under development, and aspirations for the coming decade.
Thursday Apr 28, 10:30
Ciaran O'Hare (University of Sydney)
Colloquium: New discoveries from the Gaia satellite, and direct searches for dark matter
The recent releases of data from the Gaia satellite have been transformational for galactic astronomy. The unprecedented accuracy with which stellar positions and velocities can be determined with Gaia means we are getting a fresh understanding of the structure, composition and history of the Milky Way. The new data shows that the Milky Way underwent several major merger events which shaped the kinematic structure of its stellar halo in surprising ways. As the stellar halo and the dark matter halo are closely linked, this new evidence will have important consequences for experiments searching for dark matter on Earth. In some cases, like underground searches for particle-like dark matter, Gaia allows us to update the standard halo assumptions used in modelling expected signals. In other cases, notably searches for wave-like dark matter, the relics of our Milky Way's past may be much more readily observable.
Tuesday Apr 26, 10:30
Geray Karademir ()
Student Review: Faint Luminosity Functions from Clustering-based Redshifts (DTR)
Time: Apr 26, 2022 10:30 AM Australia/Melbourne
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Wednesday Apr 20, 10:30
Christian Lehmann ()
Student Review: Christian Lehmann's Draft Thesis Review
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Thursday Apr 14, 10:30
Christene Lynch (ICRAR-Curtin)
Colloquium: The MWA Long Baseline Epoch of Reionisation Survey
One of the principal systematic constraints on the Epoch of Reionisation (EoR) experiment is the accuracy of the foreground calibration model. Recent results have shown that highly accurate models of extended foreground sources, and including models for sources in both the primary beam and its sidelobes, are necessary for reducing foreground power. To improve the source models in the EoR fields observed by the Murchison Widefield Array (MWA), we conducted the Long Baseline Epoch of Reionisation Survey. This survey consists of multi-frequency observations, spanning 104-230 MHz, of the MWA EoR fields and their eight neighbouring fields using the MWA Phase II extended array. These observations provide high-resolution, UV-components to compliment the existing UV-plane sampling of these fields. Additionally, due to the better imaging capabilities of the MWA Phase II extended array, this survey improves upon the sensitivity of the GLEAM survey by roughly a factor of 5 in the EoR fields. This talk will present results from the first half of the LoBE survey and discuss the next steps for foreground modelling for the MWA EoR experiment.
Tuesday Apr 12, 10:30
Bron Reichardt Chu ()
Student Review: Reichardt Chu DTR
Thursday Apr 7, 16:00
Ellert van der Velden (ex-Swinburne)
Colloquium: From an astrophysics PhD to a software engineer at an energy data platform; my transition from academia to industry
In this colloquium, I will talk about my experiences with transitioning from an academic PhD to a job as a programmer in industry.

I will give an overview of the reasons why I felt leaving academia was necessary; what the skills are that industry is looking for (and how these align with what you learn as an astrophysics PhD student); and what my current job entails.
This colloquium functions both as just an overview talk of what is possible outside of academia, which should be of interest to most students, but also as an update of what I have been up to lately (as most at Swinburne will still remember me).
Thursday Mar 31, 10:30
Yuan-Sen Ting (ANU)
Colloquium: On Modelling Complex Systems in Astronomy
Astronomy today is fundamentally different than it was even just a decade ago. Our increasing ability to collect a large amount of data from ever more powerful instrumental has enabled many new opportunities. However, such opportunity also comes with new challenges. The bottleneck stems from the fact most astronomical observations are inherently high dimension - from "imaging" the Universe at the finest details to fully characterizing tens of millions of spectra which consists of tens of thousands of wavelength pixels. In this regime, classical astrostatistics approaches struggle.

I will present two different machine learning approaches to quantify complex systems in astronomy. (1) Reductionist approach: I will discuss how machine learning can optimally compress information and extract higher-order moment information in stochastic processes. (2) A generative approach: I will discuss how generative models, such as normalizing flow, allow us to properly model the vast astronomy data set, enabling the study of complex astronomy systems directly in their raw dimension.
Tuesday Mar 29, 10:30
Stuart Lyall ()
Student Review: Stuart Lyall MCR
Thursday Mar 24, 10:30
Tara Murphy (University of Sydney)
Colloquium: First results from the ASKAP Variables and Slow Transients Survey (VAST)
The ASKAP Variables and Slow Transients survey will give us an unprecedented opportunity to investigate the sky at radio wavelengths for highly variable and transient sources on timescales as short as 5 seconds. ASKAP’s wide-field survey capabilities will enable the discovery and investigation of variable and transient phenomena from the local to the cosmological including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, intra-day variables, radio supernovae and the orphan afterglows of gamma-ray bursts.

In 2021 we completed the VAST Phase I and Phase II Pilot Surveys, in preparation for full survey operations in 2022. I will present the first results from the pilot surveys, including the discovery of a new Galactic Centre Radio Transient, and discuss our plans for the upcoming full survey.
Tuesday Mar 22, 09:00
Brodie Norfolk ()
Student Review: Brodie Norfolk DTR
**Note special time** 9am start for Brodie's DTR
Friday Mar 18, 11:00
Matt Miles (Swinburne)
Student Review: Matt Miles MCR
Matt Miles's mid-candidature review.
Thursday Mar 17, 10:30
Anais Moller (Swinburne)
Colloquium: TBA
The Dark Energy Survey (DES) was designed to investigate the dynamics of the cosmic expansion. During five years, the DES Supernova Program (DES-SN) obtained light curves for tens of thousands of extragalactic transients including thousands type Ia supernovae (SNe Ia) for cosmology. In collaboration with DES, OzDES obtained spectroscopic redshifts with spectra of SNe Ia host-galaxies using the AAT.

In this talk, I will introduce analysis updates from the DES-SN survey. I will present cosmology constraints obtained from data that were taken during the first three years of the survey, containing 207 spectroscopically confirmed SNe Ia. I will then summarise work that is being done now to analyse the full dataset. I will highlight key features of our current cosmology analysis including photometric classifiers and our efforts on systematic uncertainties control.
Wednesday Mar 16, 12:00
Mohsen Shamohammadi ()
Student Review: Mohsen Shamohammadi DTR
Tuesday Mar 15, 10:30
Tyler Hughes (Swinburne)
Student Review: Tyler Hughes CoC
Zoom Link:
Thursday Mar 10, 10:30
Kelly Gourdji (Swinburne)
Colloquium: Fast radio bursts and the radio signatures of neutron star mergers
The exciting field of fast radio bursts (FRBs) has rapidly evolved, but their origin(s) remain unknown. Thanks to new radio telescopes with large fields of view, the number of known FRBs has increased drastically in recent years, ushering us into an era where the phenomena may be studied as a population. FRB 121102, on the other hand, is the first source known to repeat and its precise localisation has enabled unprecedented studies of a single source. In the first part of this talk, I show what we’ve learned over the years using sensitive Arecibo observations. In the second part of my talk, I will describe the possible connection between FRBs and neutron star mergers. In particular, I will show how we can use localised FRBs to constrain merger-related FRB models. Then, tackling the hypothesis from a different angle, I show how we are triggering the Low-Frequency Array (LOFAR) within minutes to catch prompt radio emission associated with short Gamma-ray bursts that are detected by Swift. In the final part of my talk, I will describe the LOFAR gravitational wave merger follow-up campaign of which I am PI. Here, I will discuss the later-time incoherent afterglows of merger events at low frequencies. The biggest challenge associated with detecting the electromagnetic counterpart of gravitational wave (GW) merger events, however, is the large uncertainty (tens of square degrees) on their locations. I will present our strategy which applies LOFAR’s high sensitivity and large field of view to search for GW merger radio counterparts. I will also show our latest results from O3, the last gravitational wave observing run. Finally, the wide coverage of our observations should probe most of the localisation region for binary neutron star merger events detected in the upcoming GW observing run.
Tuesday Mar 8, 10:30
Ryan Turner ()
Student Review: Ryan Turner DTR
Tuesday Mar 1, 10:30
Sera Rauhut ()
Student Review: Sera Rauhut MCR
Tuesday Mar 1, 15:00
Student Review: Adam Ussing CoC
Thursday Feb 24, 16:00
Prasun Dutta (IIT (BHU))
Colloquium: Large scale Structure and Dynamics of the interstellar medium
Gas, dust and stars make a galaxy. In the disk-shaped spiral galaxies, gas constantly feeds to star formation. Massive stars die and stir the gas, which results in turbulent motions. Later, along with gravitational instabilities, it creates fragments of isolated gas clouds, some of which overcome the pressure from thermal motion and turbulence and collapse to form a new generation of stars. We observe 21-cm spectral line emission from the neutral hydrogen gas in galaxies to probe the statistical characteristics of the structures in the column density and velocity in the interstellar medium (ISM). Our investigations show that the energy input in the interstellar medium originates at scales comparable to the size of the galaxy and cascades down to smaller scales, where it thereby influences the star formation. The methodology used to access the statistics of the column density and velocity structure, interpretation of the measurements and their importance in ISM physics will be discussed.
Wednesday Feb 23, 10:30
Juan Espejo ()
Student Review: Juan Espejo DTR
Tuesday Feb 22, 10:30
Aaron Myszka (SUT)
Student Review: Aaron Myszka MCR: Calibrating the Chemical Content of Galaxies Near and Far
Tuesday Feb 8, 10:30
Daniel McPherson ()
Student Review: McPherson MCR
Tuesday Feb 1, 10:30
Renee Key ()
Student Review: Renee Key CoC