Diskoseismology and QPOs Confront Black Hole Spin

TL;DR

This paper evaluates whether diskoseismology, specifically the fundamental g-mode, can explain QPOs in black hole binaries by comparing spin measurements from different methods, finding partial support for the g-mode origin.

Contribution

It tests the hypothesis that a specific QPO is produced by the fundamental g-mode of accretion disks, providing observational constraints on diskoseismology models.

Findings

QPOs may be produced by the fundamental g-mode.

Models linking a single QPO to the innermost stable circular orbit are inconsistent.

Comparison of spin measurements supports the g-mode hypothesis.

Abstract

We compare the determinations of the angular momentum of stellar mass black holes via the continuum and line methods with those from diskoseismology. The assumption being tested is that one of the QPOs (quasi-periodic oscillations) in each binary X-ray source is produced by the fundamental g-mode. This should be the most robust and visible normal mode of oscillation of the accretion disk, and therefore its absence should rule out diskoseismology as the origin of QPOs. The comparisons are consistent with the second highest frequency QPO being produced by this g-mode, but are not consistent with models in which one QPO frequency is that of the innermost stable circular orbit.