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2020年7月24日, 星期五

Astronomy Colloquium (06.23/2020): High-frequency variability in black hole accretion flows

日历
研讨会日历
Date
06.23.2020 12:45 pm - 1:45 pm

description

description
Meeting ID: 523 477 035
Joining Link: http://zoom.com.cn/j/523477035
Speaker:Dr. Janosz Dewberry

真人百人牛牛dr. janosz dewberry is a postdoctoral research at the tsung-dao lee institute. he received his phd in 2019 from the university of cambridge, where he worked as a member of the astrophysical fluid dynamics and non-linear dynamics research group in the department of applied mathematics and theoretical physics (damtp). janosz focuses primarily on astrophysical applications of fluid dynamics and magnetohydrodynamics. his current research interests revolve around distorted accretion disks, and rapidly rotating stars and planets.

abstract: binary systems thought to contain an accreting, stellar-mass black hole and a less evolved donor star 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 the accreting black hole. however, hfqpos remain poorly understood, despite more than 20 years of observations by the rossi x-ray timing explorer and more recent x-ray observatories. in this talk, i will discuss one explanation for hfqpos, namely the excitation of `diskoseismic' oscillations in the inner regions of a black hole accretion disk. in addition to an introduction to diskoseismology, i will describe recent analytical and numerical results related to a particular family of trapped waves, which can be excited when the inner regions of a relativistic accretion flow becomes sufficiently eccentric and/or warped.

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