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Colloquia Series

For more information on colloquia at the Centre for Astrophysics and Supercomputing please contact Dr. Joel Pfeffer or Dr. Barbara Mazzilli Ciraulo ()

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2024 Colloquia

Tuesday Nov 19, 10:30
Lydia Haacke (Swinburne)
Student Review: MCR review for Lydia Haacke
MCR review for Lydia Haacke.
Thursday Oct 3, 10:30
Tom Evans-Soma (University of Newcastle)
Colloquium: TBD
Thursday Sep 19, 10:30
Rhea-Silvia Remus (University Observatory in Munich)
Colloquium: TBC
Thursday Sep 12, 10:30
Lucas Kimmig (University Observatory in Munich)
Colloquium: TBD
Wednesday Sep 11, 10:30
Romy Pearse (AAL)
Colloquium: AAL update
Update on AAL activities
Thursday Sep 5, 10:30
Benjamin Metha (University of Melbourne)
Colloquium: TBD
Thursday Aug 29, 10:30
Gemma Anderson (Curtin University)
Colloquium: TBD
Tuesday Aug 20, 14:00
Pratyasha Gitika ()
Student Review: Pratyasha Gitika DTR
Thursday Aug 15, 10:30
Madeleine McKenzie (ANU)
Colloquium: TBD
Thursday Aug 8, 10:30
Anais Moller (CAS, Swinburne University of Technology)
Colloquium: TBD
Thursday Aug 1, 10:30
Marcus Lower (CSIRO)
Colloquium: TBD
Thursday Jul 25, 10:30
Elaine Sadler (University of Sydney)
Colloquium: TBD
Tuesday Jul 23, 10:30
Tony Pilkington (CAS)
Student Review: Tony Pilkington MCR
Thursday Jul 18, 10:30
Ahmad Nemer (Center for Astrophysics and Space Science (CASS), NYU Abu Dhabi)
Colloquium: A deeper dive into the BPT diagrams and the origin of LINER emission with machine learning
We study the SDSS-IV MaNGA database consisted of spatially resolved spectra of ~10,000 galaxies to understand the emission properties of the associated ionizing sources. With the help of the BPT diagrams’ classification scheme, we train Spender (Melchoir et al 2021) to distinguish between the different spectra based on the dominant ionizing mechanism with information from the spectra outside of the strong emission lines usually used for classification. We find that a large fraction of LINER-like emission spectra can be distinguished by stellar absorption features associated with an old, metal-rich stellar component. This consistent with previous work finding that LINER emission could be driven by a stellar population of old low-mass evolved stars.
Tuesday Jun 11, 10:30
Ashwathi Nair (Swinburne)
Student Review: Ashwathi Nair COC Review
Ashwathi Nair COC Review: Formation channels of heavy binary neutron stars
Thursday May 30, 10:30
Ivo Labbe (Swinburne)
Colloquium: Little.Red.Dots.
The first observations with the James Webb Space Telescope (JWST) have uncovered a surprising and substantial population of compact red objects at high redshift (z = 4-9), previously undetected in even the deepest Hubble data. Subsequent ultradeep spectroscopy from the UNCOVER program revealed that these objects, colloquially known as "little red dots," exhibit ubiquitous broad Balmer lines and likely host powerful active galactic nuclei (AGN). If so, we may have identified up to 99% of known AGN at z > 4. But these are not your garden-variety type 1 QSO; their properties are weird, with some estimated black hole masses comparable to the stellar masses of their host galaxies, while in other cases the spectra display clear Balmer breaks, indicative of massive evolved stellar populations. I will present what we know so far about our new intriguing little friends, and discuss implications for our picture of early galaxy and supermassive black hole evolution.
Thursday May 23, 10:30
Shanika Galaudage (Observatoire de la Cote d'Azur, Nice)
Colloquium: Meet GW230529: the gravitational wave from the merger of a ~3.6 solar mass Compact Object and a Neutron Star
We are currently in the fourth observing run (O4) for LIGO-Virgo-KAGRA (LVK). So far, the number of gravitational-wave candidates has almost doubled compared to the total number of events reported from the first three observing runs combined. The properties we infer from these observations have broad implications for the physics and evolution of massive stars, supernova mechanisms, our understanding of different sub-populations of compact binary systems, chemical enrichment of heavy elements in the Universe, and more. Recently, the LVK announced the detection of an exceptional event from O4: it's time to meet GW230529. In this talk, I will present the properties of this compact binary and discuss the astrophysical implications of this event.
Thursday May 9, 10:30
Emma Ryan-Weber (CAS, Swinburne University of Technology / ASTRO 3D)
Colloquium: Probing Reionization with high-z metals
Understanding how chemical elements are distributed in time and space across the universe provides key observational markers for the first stars. I'll summarise my team's recent efforts in tracing elements in the early universe using ESO/VLT/X-shooter via the EXQR-30 survey of intervening metal absorbers towards 42 z~6 quasars. With the benefit of the long lever arm from z=1.9 to 6.4, high sensitivity, resolution and significant number statistics, we have made meaningful inroads. Metal ions trace both chemical enrichment and the ionization state of the Circumgalactic Medium (CGM). We find that the ionization of the CGM differs significantly over the short period of cosmic time from redshift 5.5 to 6. I'll show how a decline in the incidence of intervening CIV absorbers, coupled with a rise in CII and OI complements current evidence for a late reionization continuing to occur in metal-enriched and therefore biased regions of the Universe. A flat evolution in weak MgII is also found, despite a decline in cosmic metal content. Finally, in direct comparison with JWST, I will demonstrate why medium resolution ground-based spectroscopy is essential for a complete census of the high-z CGM.
Thursday Apr 18, 10:30
Ophelie Renaud (INSA Rennes)
Colloquium: Design and programming of heterogeneous and high-performance computing systems in astronomy
In this presentation, we address the difficult problem inherent in SKA of deploying complex astronomical applications under development on efficient target architectures that have not yet been built. Resource allocation in such scenarios has a significant impact on multiple factors such as latency, memory, energy, and cost among others. Solutions such as rapid prototyping make it possible to reliably simulate and generate efficient code for this purpose. At INSA-IETR we are developing the PREESM rapid prototyping tool to automate and accelerate this process. The tool is based on numerous thesis and internship projects as well as numerous collaborations such as Rising Stars, which is the subject of my presentation. This presentation will give an overview of the project's progress in our team. We propose methods based on the SDF (Synchronous Dataflow) model and clustering techniques to facilitate the deployment of applications on complex architectures such as CPUs, GPUs, and FPGAs on one or more machines. By providing a quick and easy solution to this NP-hard problem, our methods significantly improve the efficiency of astronomical application deployment.
Wednesday Apr 10, 10:30
Akhil Jaini ()
Student Review: Akhil Jaini CoC
Akhil's CoC review talk.
Tuesday Apr 9, 10:30
Nimas ()
Student Review: Nimas MCR
Thursday Apr 4, 10:30
Mary Putman (Columbia University/ICRAR-UWA ASTRO-3D visitor)
Colloquium: Diffuse Gaseous Baryons and Fuel for a Galaxy
The majority of the baryons in the universe are in diffuse gaseous form and the quest to understand how the gas transitions to star formation fuel in a galaxy continues. I will discuss several projects that use observations and simulations to further understand this process (letting the audience choose which they would like to hear about). 1. How can we associate the phases of gas observed with different methods? 2. Are the cold clouds within a dark matter halo growing or being destroyed? 3. What does the interface between the disk and halo look like in simulations?, 4. Do dwarf galaxies have a CGM and what happens to it as a satellite galaxy?, 5. Related to the previous question, what is the census of gaseous satellites around spiral galaxies in the local Universe compared to the Local Group?
Thursday Mar 28, 10:30
Evgeni Grishin (Monash University)
Colloquium: Stellar Death and Black-Hole Mergers in Galactic Nuclei
The dynamical and hydrodynamical evolution of stars and stellar remnants is greatly affected by the dense galactic nuclei (GN) environment. We explore the complex interplay of several physical processes that shape the properties, rates and environments of nuclear transients and black hole (BH) mergers and gravitational-wave (GW) events: i) We show how stellar dynamics shape the rate and properties of stellar BH mergers, extreme mass ratio inspiral (EMRI) and tidal disruption events (TDE). ii) For active galactic nuclei (AGN), we study how the presence of an accretion disc modified the light curves of exploding supernovae and their relation to other nuclear transients. iii) We examine in detail the gravitational torques in AGN discs that drive BH's radial migration. We find that thermal torques greatly alter the existence and nature of migration traps in AGN discs, which are believed to be responsible for massive hierarchical GW mergers. We find that GW mergers predominantly occur in low-luminosity AGNs. Finally, We combine the AGN disc modelling with merger recoil kicks to further explore the parameters space and constrain the efficiency of BH mergers for different generations.
Tuesday Mar 26, 10:30
Antonia Fernandez Figueroa (Swinburne)
Student Review: MCR - Antonia Fernandez Figueroa
Thursday Mar 21, 14:30
Vanshika Kansal ()
Student Review: Vanshika Kanasal - Confirmation of Candidature
Thursday Mar 21, 09:00
Natasha Van Bemmel (Swinburne)
Student Review: Natasha's MCR
Tuesday Mar 19, 10:30
Student Review: Jacob Askew DTR
Thursday Mar 14, 10:30
Alessandro Sonnenfeld (Shanghai Jiao Tong University)
Colloquium: Weighing galaxies with strong gravitational lensing
We are living in a golden age of extragalactic astronomy: observations over broad wavelength ranges, wide fields and unprecedented depth are allowing us to uncover important details on the formation and evolution of galaxies. Yet, key quantitative aspects on the properties of galaxies remain not well constrained. The most important such aspects are the stellar mass, the star formation efficiency (how much of the initial reservoir of gass is turned into stars), and the dark matter distribution of galaxies. Lack of precise knowledge on these quantities is limiting our progress in both galaxy evolution and cosmology.
Gravitational lensing is one of the most reliable tools to measure galaxy masses at cosmological distances, and therefore offers a solution to this problem. Ongoing and upcoming missions such as Euclid and the Chinese Space Station Telescope (CSST) will enable the discovery of tens of thousands of strong lenses, opening up the era of statistical strong lensing. I will discuss the opportunities that statistical strong lensing will bring for our understanding of galaxies, as well as the challenges associated with it.
Tuesday Mar 12, 10:30
Adam Ussing ()
Student Review: DTR
Thursday Mar 7, 10:30
Martin Rey (University of Oxford)
Colloquium: Live fast, die young: how the Universe got its first chemical elements from early stars
The Universe started without the heavy elements that make the complexity of our surrounding world (e.g. carbon, oxygen). In this talk, I will showcase ground-breaking advances in the numerical modelling of how these chemical elements are produced in stars, how they are dispersed around galaxies by energetic events, and how they get ionized to power the emission and absorption lines we observe in the spectra of distant objects. Leveraging these new prediction capabilities will take us from interpreting the highest-redshift emission lines observable by JWST to the most local chemical abundances of Galactic stars, shedding a new light on how metal-poor stars enriched the Universe in the process.
Tuesday Mar 5, 14:00
Hugo Walsh ()
Student Review: Mid-Candidature Review
Tuesday Mar 5, 10:30
Student Review: Tyson Dial CoC
Tuesday Feb 27, 10:30
Student Review: CoC: Rory Elliott
Thursday Feb 15, 10:30
Kyla Adams (UWA )
Colloquium: Certain Uncertainty: Teaching quantum physics in Year 9 classrooms
When talking about interference sometimes the point gets a bit fuzzy. Do we lock onto the physics of waves? Or particles? Or somehow use both? My PhD has focused on developing appropriate language, activities and more to remove most of the challenging questions we face when talking about quantum science. I have developed a series of lessons for Year 9 students (aged 14-15) and their science teachers, that step them through the uncertainty in interference. Concepts covered include photons as packets of light energy, wave and particle models (including an improved description), probability, and momentum. The activities form a sequence of lessons from Year 3 to 10 as part of the Einstein-First program. Through tests and interviews I have found that the students understanding changed because of the program. Students became more certain in their understanding of the uncertainty of quantum science.
Tuesday Feb 13, 10:30
Renee Key ()
Student Review: DTR: Renee Key
Friday Feb 9, 10:30
Tyler Hughes (Swinburne)
Student Review: Tyler DTR - detecting dark matter substructure with gravitational lensing
Thursday Feb 8, 10:30
Steve Schulze (Northwestern University)
Colloquium: Searching for pair-instability supernovae with current and future surveys
Observations of stellar nurseries, and massive stars and their fates have led to stellar evolution models of ever-increasing complexity. These models also predict the existence of stars with more than 100 solar masses, which may have no analogues in the local Universe, and exotic types of stellar explosions. One of those predicted, yet not securely discovered object classes, are pair-instability supernovae (PISNe). Confirming or refuting their existence and measuring their properties are critical for stellar evolution theory, supernova science and gravitational wave astronomy. In this talk, I will give an overview of the current search efforts for PISNe, discuss the properties of the most promising candidate and the challenges it imposes on theoretical models and how we can leverage that to find PISNe with the Vera Rubin Observatory Legacy Survey of Space and Time and upcoming space missions.
Tuesday Feb 6, 10:30
Alma Sebastian (Swinburne)
Student Review: Alma Sebastian MCR
Thursday Feb 1, 10:30
Andy Casey (Monash University)
Colloquium: Fantastic stars and how to find them
We have collected stellar spectra for more than 210 million stars in our galaxy. In this talk I will argue that there is good reason for that: stellar spectra are uniquely informative tracers of cosmic evolution. The age and composition of stars trace the formation of the universe across many orders of magnitude in both space and time. For example, in our local neighbourhood the most ancient stars can tell us about star formation at redshifts higher than what is possible with JWST, and the more common stars are explaining missing physics in stellar evolution, nucleosynthesis, and planet formation. I will describe our efforts to collect even more spectra through SDSS-V. I will include some stunning results from the new Local Volume Mapper instrument. And I'll explain some broadly applicable data analysis methods that we have developed to enable this stellar science.
Tuesday Jan 30, 10:30
Atharva Kulkarni ()
Student Review: Atharva Kulkarni MCR