Wednesday, October 24, 2018
4:00 PM - 5:00 PM
Cahill, Hameetman Auditorium

Astronomy Colloquium

Recent Observational Puzzles from Tidal Disruption Flares: Towards Viable Probes in the LSST Era
Brad Cenko, NASA,

I will present an overview of efforts across the electromagnetic spectrum to identify and study tidal disruption flares (TDFs), when a star wanders too close to a super-massive black hole and is torn apart by tidal forces. In particular I will focus on three unexpected surprises that challenge the most basic picture of these events: 1) large inferred radii for the optical/UV-emitting material, indicating either circularization of the bound debris at large distances and/or significant reprocessing of the radiation from the inner accretion disk; 2) the ubiquity of outflows, detected at radio, X-ray, and UV wavelengths, ranging from speeds of 100 km/s to near the speed of light; and, 3) the peculiar atomic abundances observed in the UV and optical spectra of these objects. Understanding the nature of the broadband emission will be critical if we wish to ultimately utilize these events as probes of black hole mass in distant quiescent galaxies in the LSST era. Finally I will provide an introduction to upcoming and proposed wide-field surveys that will help us address these issues in the coming years.

For more information, please contact Althea E. Keith by phone at 626-395-4973 or by email at aek@astro.caltech.edu.