University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, February 12, 2018
Coffee, Tea & Snacks 4:15-4:30 PM

Demos Kazanas
NASA Goddard Space Flight Center
MHD Accretion Disk Winds as
X-Ray Absorbers Across the Black Hole Mass Scale

Black hole accretion disks appear to produce invariably plasma outflows that result in blue-shifted absorption features in their X-ray and UV spectra. The X-ray absorption-line properties of these outflows are quite diverse, ranging in velocity from non-relativistic (∼300 km/sec) to sub-relativistic (∼0.1c where c is the speed of light) and a similarly broad range in the ionization states of the wind plasma. It will be shown that semi-analytic, self-similar magnetohydrodynamic (MHD) wind models can successfully account for the X-ray absorber properties of supermassive black holes and also that the same models fit well the high-resolution X-ray spectrum of the accreting stellar-mass black hole, GRO J1655-40. This provides an explicit theoretical argument of their MHD origin (aligned with earlier observational claims) and supports the notion of a universal magnetic structure of the observed winds across all known black hole sizes. Most importantly, these results indicate that the mass flux of these winds increases with radius, a fact that bears on the global structure of Active Galactic Nuclei (AGN) and Galactic X-Ray Sources (XRB).

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Victoria at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.