DTR review, in person only

TBA

TBA

This will be primarily an ***in-person*** review in the VR Theatre. Please physically come along!

Detections of the neutral hydrogen 21cm line in absorption can provide a powerful tool in understanding the role that cold gas plays in the formation and evolution of galaxies. The First Large Absorption-line Survey for HI (FLASH) takes advantage of the wide bandwidth, frequency range and radio-quiet site of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for HI out to redshifts of z=1, a parameter space which has been poorly explored until now. In this talk I will present an overview of the science case for the FLASH survey and show some early results obtained from pilot survey observations carried out last year.

For the last half-century, relativistic outflows accompanying the final collapse of massive stars have predominantly been detected via high-energy emission, as long-duration gamma-ray bursts (GRBs). From wide-field optical and radio time-domain surveys, there have been hints of related phenomena at lower energies, such as X-ray flashes. With the Zwicky Transient Facility (ZTF) we are conducting a systematic exploration of the broader landscape of engine-driven explosions, of which traditional GRBs are just one manifestation. The emerging zoo includes afterglows at cosmological distances with no detected GRB, broad-lined Ic (Ic-BL) supernovae with luminous X-ray and radio emission, and fast-luminous transients powered by circumstellar interaction such as AT2018cow. Understanding the origin of these events and their relation to GRBs will require coordinated observations between high-cadence optical surveys, wide-field gamma-ray monitors, and millimeter and radio observatories. This will be possible in the next few years with the launch of the Space-based multi-band astronomical Variable Objects Monitor (SVOM), the enhanced cadence of ZTF Phase II, and sensitive millimeter-band facilities like the Atacama Large Millimeter Array (ALMA).

The detection of gravitational waves and electromagnetic radiation from a neutron star merger, GW170817, heralded the dawn of a new age of astronomy - the multi-messenger era. In this talk, I will discuss follow-up of two landmark gravitational wave events - GW170817 and GW190814. Radio monitoring of GW170817 enabled tight constraints to be placed on the geometry and energetics of the merger, while VLBI imaging helped improve the "standard siren" measurement of the Hubble constant. No counterpart to GW190814 has been detected, but we have carried out 8 follow-up observations with ASKAP, covering ~90% of the localisation region. We have used these observations to carry out the most sensitive widefield radio transient survey to-date, and I will also present preliminary results from this search. I will outline prospects for radio follow-up of future gravitational wave events including the vital contributions that radio observations can make to the broader multi-messenger effort, and quantitative estimates for the detectability of events with current and future facilities.

Time: Mar 16, 2021 10:30 AM Australia/Melbourne
Join from a PC, Mac, iPad, iPhone or Android device:
Please click this URL to start or join: https://swinburne.zoom.us/j/84644651795

Meeting ID: 846 4465 1795

This is Matthew Miles's CoC presentation.

Our current understanding of galaxy evolution hinges on the assumption that the universe has Solar-scaled metallicity abundances, which is not applicable outside our Solar System. This prohibits progress in understanding how the distribution of the metals in stars are recycled into the interstellar gas of galaxies throughout cosmic time. In this talk, I will present the first set of massive stellar evolutionary models developed that are computed self-consistently in all the input parameters of the models. These models are based on physically realistic metal abundances in HII regions using the Galactic Concordance scaling system, which allows us, for the first time, for us to accurately compare stellar observations against models that are not constrained solely against a single star, the Sun. The evolutionary tracks for our Galactic Concordance abundance scaling provide a more physically motivated approach than simple uniform abundance scaling with metallicity for the analysis of HII regions and have considerable implications in determining nebular emission lines and metallicity. As the surface enhancement of elements in massive rotating stars have broad impact on the ionizing spectra of high-redshift, low-metallicity galaxies, such stellar models with realistic, variable metallicities need to be considered to accurately model and predict the properties of galaxies across cosmic time.

CoC

Supernovae are explosive endpoints of stellar evolution. The most common two categories are core-collapse supernovae and thermonuclear supernovae. In core-collapse supernovae, the kinetic energy of the explosion is provided by the gravitational energy released when the iron core of an evolved massive star collapses to either a neutron star or a black hole. Open questions include how stripped supernovae lose their envelopes and which core-collapse supernovae make black holes and which make neutron stars. In part I of my talk, I will present examples of how optical integral field observations of the remnants of certain core-collapse supernovae, such as 1E0102.2-7219 or Puppis A, provide us with puzzling new structures that need to be understood if we want to make progress on the nature of their supernova progenitors.
In thermonuclear supernovae, the energy source is explosive nuclear fusion in white dwarf stars of lighter elements like helium, carbon, and oxygen, to heavier elements like silicon or nickel and iron. What kind of white dwarfs explode and how they evolve to ignition are still largely open questions.
In part II of my talk, I will present the recently discovered optical coronal line emission of the reverse shocked ejecta in three young thermonuclear supernova remnants and discuss a new approach to how these optical emission lines can be modelled to infer key parameters of the original supernova, such as explosion energy and mass.

TBD

https://swinburne.zoom.us/j/82298144371?pwd=STd3OWE2YmU1RlVmRVZoT0Jld0tEZz09