Radiative plasma simulations of black hole accretion flow coronae in the hard and soft states

TL;DR

This study uses advanced radiative plasma simulations to show how turbulence and quantum electrodynamics influence the emission states of black hole accretion flow coronae, explaining the origin of hard and soft X-ray states.

Contribution

It introduces self-consistent simulations including quantum electrodynamics, revealing how turbulence and irradiation drive state transitions in black hole coronae.

Findings

Turbulent plasma naturally produces hard-state emission.

Soft X-ray irradiation causes plasma to transition to soft-state emission.

Quantum electrodynamics processes govern plasma state and emission characteristics.

Abstract

Stellar-mass black holes in x-ray binary systems are powered by mass transfer from a companion star. The accreted gas forms an accretion disk around the black hole and emits x-ray radiation in two distinct modes: hard and soft state. The origin of the states is unknown. We perform radiative plasma simulations of the electron-positron-photon corona around the inner accretion flow. Our simulations extend previous efforts by self-consistently including all the prevalent quantum electrodynamic processes. We demonstrate that when the plasma is turbulent, it naturally generates the observed hard-state emission. In addition, we show that when soft x-ray photons irradiate the system -- mimicking radiation from an accretion disk -- the turbulent plasma transitions into a new equilibrium state that generates the observed soft-state emission. Our findings demonstrate that turbulent motions of magnetized plasma can power black-hole accretion flow coronae and that quantum electrodynamic processes control the underlying state of the plasma.