TY - JOUR
AU - Jason Dexter
AU - Nicolas Scepi
AU - Mitchell Begelman
AB - We present global radiation GRMHD simulations of strongly magnetized accretion onto a spinning, stellar mass black hole at sub-Eddington rates. Using a frequency-dependent Monte Carlo procedure for Compton scattering, we self-consistently evolve a two-temperature description of the ion-electron fluid and its radiation field. For an Eddington ratio L/LEdd≳10−3, the emergent spectrum forms an apparent power law shape from thermal Comptonization up to a cutoff at ≃100 keV, characteristic of that seen in the hard spectral states of black hole X-ray binary systems. At these luminosities, the radiative efficiency is high (≈24%) and results in a denser midplane region where magnetic fields are dynamically important. For L/LEdd∼10−2, our hot accretion flow appears to undergo thermal runaway and collapse. Our simulations demonstrate that hot accretion flows can be radiatively efficient and provide an estimate of their maximum luminosity.
BT - The Astrophysical Journal Letters
DA - 2021-09
DO - 10.3847/2041-8213/ac2608
IS - 2
N2 - We present global radiation GRMHD simulations of strongly magnetized accretion onto a spinning, stellar mass black hole at sub-Eddington rates. Using a frequency-dependent Monte Carlo procedure for Compton scattering, we self-consistently evolve a two-temperature description of the ion-electron fluid and its radiation field. For an Eddington ratio L/LEdd≳10−3, the emergent spectrum forms an apparent power law shape from thermal Comptonization up to a cutoff at ≃100 keV, characteristic of that seen in the hard spectral states of black hole X-ray binary systems. At these luminosities, the radiative efficiency is high (≈24%) and results in a denser midplane region where magnetic fields are dynamically important. For L/LEdd∼10−2, our hot accretion flow appears to undergo thermal runaway and collapse. Our simulations demonstrate that hot accretion flows can be radiatively efficient and provide an estimate of their maximum luminosity.
PY - 2021
EP - L20
T2 - The Astrophysical Journal Letters
TI - Radiation GRMHD Simulations of the Hard State of Black Hole X-ray Binaries and the Collapse of a Hot Accretion Flow
UR - https://iopscience.iop.org/article/10.3847/2041-8213/ac2608
VL - 919
ER -