Dr. Kate Alexander, Assistant Professor,UArizona Steward Observatory
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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 creation and merger of neutron stars and black holes, and the tidal disruption of stars by supermassive black holes. I will discuss my ongoing work on the formation and structure of relativistic jets and outflows in the most extreme astrophysical transients, including gamma-ray bursts (GRBs; powerful jets launched by the deaths of massive stars or the mergers of neutron stars and black holes) and tidal disruption events (TDEs). I will show that radio data provide the best constraints on the immediate environments of these transients, probing models of black hole growth and accretion (TDEs) and stellar evolution models (GRBs). I will discuss my exciting ongoing observations of TDEs and GRBs, which reveal an unexpectedly diverse population. The exquisite new datasets obtained for individual objects challenge our existing understanding of jets, as exemplified by the recent GRB 221009A, the brightest GRB expected in 10,000 years. In the near future, new observational and multi-messenger capabilities will provide the first large samples of rare, relativistic events and move transient science into the statistical realm.