The X-ray Binary Analogy to the First AGN QPO

TL;DR

This paper compares a unique AGN QPO with stellar-mass black hole QPOs, suggesting a mass-scaled analogy that supports unified accretion flow models across different black hole sizes.

Contribution

It identifies the AGN QPO with the 67Hz QPO in GRS 1915+105, providing evidence for mass scaling of accretion properties between stellar and supermassive black holes.

Findings

AGN QPO likely corresponds to GRS 1915+105's 67Hz QPO

Broadband power spectral shapes are similar between AGN and BHB

Supports mass scaling of accretion flow properties

Abstract

The Narrow Line Seyfert 1 galaxy REJ1034+396 is so far unique amongst AGN in showing a Quasi-periodic oscillation (QPO) in its variability power spectrum. There are multiple types of QPO seen in black hole binary (BHB) systems, so we need to identify which BHB QPO corresponds to the one seen in the AGN. A key hint is the `hot disc dominated' energy spectrum of REJ1034+396 which is sufficiently unusual that it suggests a mildly super-Eddington flow, also favoured by the most recent mass estimates for the AGN. This suggests the 67Hz QPO seen occasionally in the mildly super-Eddington BHB GRS 1915+105 as the most likely counterpart, assuming mass scaling of the QPO frequency. This is supported by the fact that these data from GRS 1915+105 have an energy spectrum which is also dominated by a `hot disc' component. Here we show that the underlying broad band power spectral shape and normalisation are also similar, providing further consistency checks for this identification. Thus the AGN QPO adds to the growing evidence for a simple mass scaling of the accretion flow properties between stellar and supermassive black holes.