Speaker: Yajie Yuan (Princeton University)
Date:  Monday, November 19th, 2018
Time: 3:30 PM - 4:30 PM (Refreshments @ 3:00 pm)
Location:  Physical Sciences Complex Room 1136, University of Maryland, College Park

"Heating of the Compact X-ray Corona in Seyfert Galaxies"
There is observational evidence that the X-ray continuum source that creates the broad fluorescent emission lines in some Seyfert Galaxies may be compact and located at a few gravitational radii above the black hole. We consider two scenarios for the X-ray emission. The first possibility is that the X-rays may be produced by particles accelerated in an electrostatic gap at the base of a putative jet. However, our detailed study of the gap kinetic physics and scaling suggests that the energetics is not enough in these environments. The second possibility is that the compact X-ray emitting source may be powered by small scale flux tubes near the black hole that are attached to the orbiting accretion disk. Our force-free simulations show that the field linking the black hole and the disk can get twisted up by the differential rotation to form a magnetic tower. When the confinement provided by the field from the outer disk is strong, the built-up magnetic tower can quickly become kink unstable, which leads to continuous reconnection and dissipates most of the energy extracted from the rotating black hole. This could in principle power a hot X-ray emitting region above the black hole.       

Parking:  You may park in the Regents Drive Parking Garage located directly across from the Physical Sciences Complex.  All Pay Station Parking is now located on the top floor of the garage.  Please use parking code 883-00325 for this event.  This parking code is good for 11/19/18 only.