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GRMHD Simulations of Misaligned and Truncated Accretion Disks

Presentation #110.91 in the session “Stellar/Compact (Poster)”.

Published onApr 01, 2022
GRMHD Simulations of Misaligned and Truncated Accretion Disks

In recent years the H-AMR collaboration has performed the first self-consistent general relativistic magnetohydrodynamics (GRMHD) simulations of misaligned (wrt to black hole spin axis) geometrically thin accretion disks, which can be found in the luminous spectral states of accreting black holes. In this talk I will describe the latest findings of our group, which include the discovery that such disks can be torn apart by the Lense-Thirring torque from a rapidly spinning black hole. I will demonstrate that disk tearing leads to precession of the inner disk and can explain both low and high-frequency quasi-periodic oscillations (QPOs) observed in XRB lightcurves. I will sketch out an unified theory describing the generation of QPOs and discuss the implications of these findings on e.g. black hole spin measurements. I will discuss the next generation of GRMHD simulations performed in the H-AMR group, which include a self-consistent treatment of radiation and two-temperature physics. I will demonstrate that the presence of large scale poloidal magnetic flux can self-consistently lead to the formation of a ‘truncated’ accretion disk, where a geometrically thin accretion disk feeds a hot 2-phase corona consisting out of hot electrons and extremely hot ions. I will discuss the physics driving the formation and evolution of this corona, including the associated (jetted) outflows. I will demonstrate that cold patches of gas can penetrate this hot corona, which can potentially lead to relativistically broadened iron lines.

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