Stellar-mass black holes on the millimetre fundamental plane of black hole accretion

TL;DR

This paper demonstrates that stellar-mass black holes, like supermassive ones, follow a fundamental plane relating millimetre luminosity, X-ray luminosity, and black hole mass, with implications for accretion models.

Contribution

It extends the galaxy fundamental plane of black hole accretion to stellar-mass black holes using millimetre and X-ray data, confirming its applicability across mass scales.

Findings

XRBs lie on the millimetre fundamental plane similar to AGNs.

Deviations occur after state changes, indicating the plane's applicability to the hard state.

Both accretion flow and jet models support the existence of the plane.

Abstract

Recent work revealed the existence of a galaxy "millimetre fundamental plane of black hole accretion", a tight correlation between nuclear $1$mm luminosity, intrinsic $2$ - $10$keV X-ray luminosity and supermassive black hole mass, originally discovered for nearby low- and high-luminosity active galactic nuclei. Here we use mm and X-ray data of $5$ X-ray binaries (XRBs) to demonstrate that these stellar-mass black holes also lie on the mm fundamental plane, as they do at radio wavelengths. One source for which we have multi-epoch observations shows evidence of deviations from the plane after a state change, suggesting that the plane only applies to XRBs in the hard state, as is true again at radio wavelengths. We show that both advection-dominated accretion flows and compact jet models predict the existence of the plane across the entire range of black hole masses, although these models vary in their ability to accurately predict the XRB black hole masses.