The variability plane of accreting compact objects

TL;DR

This paper extends the variability plane concept to include different states of accreting compact objects, revealing a unified scaling relation among black holes, neutron stars, and white dwarfs, with implications for understanding accretion physics.

Contribution

It introduces a unified variability plane that encompasses soft and hard states of black holes, neutron stars, and white dwarfs, accounting for state transitions and additional parameters.

Findings

The variability plane applies across different accreting objects and states.

Frequency, mass, and accretion rate are correlated with a state-dependent offset.

The relationship suggests a common physical mechanism underlying diverse accreting systems.

Abstract

Recently, it has been shown that soft-state black hole X-ray binaries and active galactic nuclei populate a plane in the space defined by the black hole mass, accretion rate and characteristic frequency. We show that this plane can be extended to hard-state objects if one allows a constant offset for the frequencies in the soft and the hard state. During a state transition the frequencies rapidly move from one scaling to the other depending on an additional parameter, possibly the disk-fraction. The relationship between frequency, mass and accretion rate can be further extended by including weakly accreting neutron stars. We explore if the lower kHz QPOs of neutron stars and the dwarf nova oscillations of white dwarfs can be included as well and discuss the physical implications of the found correlation.