Presentation Archive

High-frequency variability in black hole accretion flows

Janosz Dewberry (CITA)

November 02, 2020

Abstract: X-ray binaries thought to contain a stellar-mass, accreting black hole occasionally exhibit rapid variability, at frequencies of roughly ~50-450 Hz. These “high-frequency, quasi-periodic oscillations” (HFQPOs) attract significant theoretical interest because their frequencies appear to be set by the intrinsic properties of black hole. However, HFQPOs remain poorly understood, despite decades of observations by the Rossi X-Ray Timing Explorer and newer X-ray observatories. In this talk, I will discuss one explanation for HFQPOs, namely the excitation of “diskoseismic” oscillations in a black hole accretion disk. In addition to introducing diskoseismology, I will describe analytical and numerical results regarding a particular family of magnetohydrodynamic waves that can be excited when the inner regions of a relativistic accretion flow become sufficiently eccentric and/or warped.