The variability plane of accreting compact objects

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 disc fraction. The relationship among frequency, mass and accretion rate can be further extended by including weakly accreting neutron stars (NSs). We explore if the lower kHz quasi-periodic oscillations of NSs and the dwarf nova oscillations of white dwarfs can be included as well and discuss the physical implications of the found correlation.