Black-hole discoseismic oscillations and instabilities in eccentric astrophysical discs

by Janosz Dewberry (University of Cambridge)

Wednesday 8 May 2019, 13:30 → 14:30 Asia/Shanghai

Meeting Room 202, Tsung-Dao Lee Institute (East wing of Pao Yue-Kong Library)

Abstract

High-frequency, quasi-periodic oscillations (HFQPOs) observed in the emission from galactic black hole binaries present an important but unresolved problem in astrophysics. An attractive explanation offered by hydrodynamic theory involves the excitation of `discoseismic' oscillations in the inner regions of a black hole accretion disk, where they are confined by relativistic effects. However, magnetic fields can significantly alter the dynamics of such pulsations, which additionally require a driving mechanism to reach observable amplitudes. I present a magnetohydrodynamic analysis of the effects of magnetic fields with different geometries on so-called trapped inertial waves, and numerical simulations exhibiting the modes' excitation to large amplitudes through non-linear coupling with eccentric disk deformations. I additionally present preliminary results regarding more fundamental aspects of both global mode and local wave excitation in eccentric discs.

Biography

Janosz Dewberry works on various problems on astrophysical accretion disks.
He will receive his Ph.D. in the May from DAMTP at University of Cambridge.
He will join T.D.Lee Institute as a postdoctoral fellow in Fall 2019.

Division

Astronomy and Astrophysics