Speaker: Philip Wiseman (University of Southampton)
Title: Transients on the Edge
Abstract: Astrophysical transients — temporary fireworks illuminating the Universe — are unique tools that allow us to study physics on all scales. This year, two revolutionary feats of engineering will allow the study of transients like never before. The Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST) will soon be discovering hundreds of thousands of transients per year. To provide deeper insights on this giant dataset, the Time Domain Extragalactic Survey (TiDES) will classify over 30,000 transients and obtain spectra of a further 100,000, mapping transient parameter space in exquisite detail.
I am interested in two distinct regions of this parameter space. Type Ia supernovae are the explosions of white dwarf stars and, due to their very uniform peak luminosities, have led the effort to measure distances and infer cosmological parameters for the last 30 years. With modern surveys achieving increasingly precise measurements of dark energy, subtle correlations between the supernovae and properties of their host galaxies threaten to limit this progress. I will show how LSST and TiDES will address and overcome these issues.
Secondly, I will discuss a relatively new, puzzling type of transient: extremely long lived, luminous flares from the centres of galaxies. These ambiguous nuclear transients (ANTs) are too bright and have different spectra from regular tidal disruptions of stars by massive black holes, but are equally unable to be explained by a standard steady-state active galactic nucleus. LSST will increase the sample of ANTs by an order of magnitude. I will highlight the excitement and challenges faced trying to understand what they are and their important role in galaxy evolution.
Room: Sala de Reuniões e Seminários (2-8.3, 2nd Floor of Physics Building)