Cosmic Extremes

- Time-Domain Astronomy in a Multi-Messenger World -

Abstract:  Time-domain astrophysics provides a unique opportunity to study the most extreme physical processes in the Universe, including the deaths of massive stars, the destruction and creation of compact objects like neutron stars and black holes, and the tidal disruption of stars by supermassive black holes (SMBHs). I will discuss recent results that reveal the formation and structure of relativistic jets and outflows in the most extreme classes of astrophysical transients, including gamma-ray bursts (GRBs) and tidal disruption events (TDEs). I will show that radio data provide the best constraints on the density of the surrounding medium, probing models of SMBH growth and accretion (TDEs) and stellar evolution models (GRBs). Finally, I will briefly discuss the bright future of time-domain astrophysics. With the pioneering detections of gravitational waves, astronomers and physicists have gained a new, complementary tool to study compact object mergers, with important implications for fields as wide-ranging as general relativity, nuclear physics, shocks and cosmology. Collaboration with LIGO and its successor gravitational wave observatories will enable precision constraints on merger physics, while upcoming surveys like LSST will provide the first large samples of rare, relativistic events and move transient science into the statistical realm. Simultaneously, new radio interferometers like the ngVLA and the Square Kilometer Array are poised to transform radio astronomy, revealing the radio sky in unprecedented depth and leading to the discovery of relativistic transient populations in the radio band.

Bio:  Dr. Alexander is a NASA Hubble Fellowship Program Einstein Postdoctoral Fellow at Northwestern University. Her research focuses on extreme events in the cosmos: stellar explosions, neutron star mergers, and transient accretion episodes onto supermassive black holes resulting from the tidal disruption of stars. She received her Ph.D. in Astronomy & Astrophysics from Harvard University in 2018, where she was a NSF Graduate Research Fellow. Previously, she received a Sc.B. in physics from Brown University in 2012.

Refreshments will be served afterwards in the PandA Café.