Scale-invariance of black hole accretion: modelling emission from a black hole X-ray binary with relativistic accretion flow simulations

Abstract

We model non-thermal emission spectrum of the extremely sub-Eddington X-ray binary system A0620-00. It is believed that this non-thermal emission is produced by a radiatively inefficient "quiescent" accretion onto a stellar-mass black hole present in the system. We post-process GRMHD simulations with multiwavelength, fully polarized, relativistic radiative transfer calculations to predict broadband spectra and emission polarization levels for a range of electron models and accretion rates. We find that a model with strong coupling of electrons and ions in the accretion disk and accretion rate of onlyṀ = 3 × 10 −13 [M yr −1 ] is able to recover the observed X-ray spectral slope as well as the excess of linear polarization detected in the source in NIR/optical bands. Our models constrain the spectral properties of a putative relativistic jet produced in this system. In addition we show that the magnetized winds from our hot accretion flow carry away a small fraction of the orbital angular momentum of the binary unable to explain the observed rapid orbital decay of the system. Similar to the present GRMHD simulations are often used to explain emission from sub-Eddington supermassvie black holes in Sgr A* or M87; the present simulations allow us to test whether some aspects of the quiescent black hole accretion are scale invariant.

High-soft to Low-hard State Transition in Black Hole X-Ray Binaries with GRMHD Simulations

“…Nonetheless, simulation for a realistic timescale (hours to tens of days) of an outburst is challenging, especially using general relativistic magnetohydrodynamics (GRMHD). The framework of GRMHD is indispensable for studying physics around BHs (see Mościbrodzka 2019;Davis & Tchekhovskoy 2020;Dexter et al 2021;Mizuno 2022, references therein).…”

Towards a larger sample of radio jets from quiescent black hole X-ray binaries

“…Radio detections of quiescent BHXB jets are important for self-consistently modeling the higher-energy radiation outputted by quiescent systems (e.g., McClintock et al 2003;Yuan & Cui 2005;Malzac 2014;Markoff et al 2015;Plotkin et al 2015;Connors et al 2017;Mościbrodzka 2019). Constraints on quiescent radio jet variability are also starting to emerge.…”