Why haven't the observed high-frequency QPOs been produced by (MHD) computer simulations of black hole accretion disks?

TL;DR

This paper examines why current MHD simulations of black hole accretion disks fail to produce observed high-frequency QPOs, highlighting issues with simulation duration and numerical damping.

Contribution

It compares theoretical predictions with simulation results, identifying key limitations in current MHD simulation approaches for high-frequency QPOs.

Findings

MHD simulations were not run long enough to produce QPOs

Numerical damping was too high in simulations

Hydrodynamic simulations showed g-modes not seen in MHD

Abstract

We compare some predictions of Wagoner & Tandon (2021) with the results of the hydrodynamic and magnetohydrodynamic (MHD) simulations of Reynolds & Miller (2009). It appears that the MHD simulations were not run for long enough and the numerical damping was not small enough to produce the observed high-frequency QPOs (and the g-mode seen in the hydro simulations).