CGCA Seminars

Can black holes evaporate past extremality?
Professor Samuel E. Gralla
University of Arizona

Black holes with sufficiently large initial charge and mass will Hawking-evaporate towards the extremal limit. The emission slows as the temperature approaches zero, but still reaches the point where a single Hawking quantum would make the object superextremal, removing the horizon. We take this semiclassical prediction at face value and ask: When the emission occurs, what is revealed?

Frame-Dragging Reveals Central Engine of a Superluminous Supernova
Dr. Logan Prust
Center for Computational Astrophysics - Simons Foundation

Type I superluminous supernovae (SLSNe-I) are an order of magnitude brighter than standard supernovae, with the internal power source for their luminosity still unknown. The central engines of SLSNe-I are hypothesized to be magnetars, but many SLSNe-I light curves exhibit multiple bumps or peaks that are unexplained by the standard magnetar model.

The masses and radii of the neutron stars observed by NICER
Prof. Sharon Morsink
University of Alberta

Neutron stars are the densest known gravitationally-stable objects in the Universe. Their strong gravitational fields, rapid rotation rates, and supra-nuclear central densities allow for a fascinating interplay between general relativistic effects and nuclear physics theory. Pulse-profile modeling is a technique that uses the gravitationally-lensed X-ray flux emitted from hot spots on the neutron star's surface to infer its mass and radius. General relativity is a crucial ingredient in this analysis.