Monday, October 11, 2021 at 12:40

JILA Auditorium and https://cuboulder.zoom.us/j/96468671083

Javier Garcia, CalTech

"Probing the Space-Time near Accreting Black Holes"

Abstract:

Astrophysical black holes of all masses, as well as neutron stars, display a very similar behavior when observed in an active mode of mass accretion. In X-rays, where these systems emit most of their radiation, the observed spectrum typically displays signatures of disk reflection, i.e., spectral features that arise due to the reprocessing of high-energy photons in the material that orbits the compact object forming an accretion disk. These signatures are great diagnostic tools for the state and composition of the gas in the disk, and can be used to probe relativistic effects in the space-time distorted by the strong gravitational field. In this talk I will describe how spectral and timing techniques are implemented to learn crucial information on these systems, such as the spin of black holes; the geometry, properties, and evolution of the disk and X-ray corona; and the detailed microphysics of the plasma orbiting the compact object. I will discuss the development of advanced reflection codes, and present several cases in which these models are providing a unique perspective to interpret the observational data from these systems.

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