A General Relativistic Magnetohydrodynamic Model of High Frequency Quasi-periodic Oscillations in Black Hole Low-Mass X-ray Binaries

TL;DR

This paper proposes a general relativistic MHD model explaining high frequency QPOs in black hole binaries through stable Alfén wave modes, accounting for observed frequency ratios and black hole mass relations.

Contribution

It introduces a novel model based on solving GRMHD equations that explains the origin of high frequency QPOs with specific frequency ratios in black hole systems.

Findings

Identifies two stable Alfén wave modes in accretion disks with toroidal magnetic fields.

Explains the 3:2 frequency ratio observed in high frequency QPOs.

Accounts for the correlation between black hole mass and QPO frequency.

Abstract

We suggest a possible explanation for the high frequency quasi-periodic oscillations (QPOs) in black hole low mass X-ray binaries. By solving the perturbation general relativistic magnetohydrodynamic equations, we find two stable modes of the Alf\'ven wave in the the accretion disks with toroidal magnetic fields. We suggest that these two modes may lead to the double high frequency QPOs if they are produced in the transition region between the inner advection dominated accretion flow and the outer thin disk. This model naturally accounts for the 3 : 2 relation for the upper and lower frequencies of the QPOs, and the relation between the black hole mass and QPO frequency.