Angular Momentum Transport across Accretion States around a rapidly spinning black hole
Abstract
Accretion requires the outward transport of angular momentum, but the relative contributions of matter advection, turbulent stresses, ordered magnetic fields, winds, and black-hole spin remain uncertain in strongly magnetized flows. We use high-resolution three-dimensional GRMHD simulations around a rapidly rotating black hole (a=0.998) to compare SANE, intermediate-flux, and magnetically arrested disk states. In SANE and intermediate states, outward stresses are insufficient to overcome inward angular-momentum advection, and the net flux remains inward. In MAD, ordered Maxwell stresses regulate the disk and drive winds, while the Blandford-Znajek jet carries a distinct, near-constant flux extracted from the black hole, making the total angular-momentum flux outward. Magnetic-flux eruptions modulate both channels. During an eruption, an equatorial current sheet extends beyond the ergosphere, and low-density, magnetically dominated bubbles of expelled flux enter the polar region. The jet becomes asymmetric, its tilt more than doubles, and its opening angle first widens and then contracts below its pre-eruption value. Eruptions suppress the horizon accretion rate and briefly reverse the angular-momentum flux through the jet surface, while reorganizing the Maxwell stresses in the disk. As horizon-threading flux re-accumulates, the turbulent stress recovers toward its saturated MAD level. Eruption durations and lags among horizon flux, accretion rate, and jet tilt of ~40-90 rg/c correspond to milliseconds for stellar-mass black holes and tens of minutes for Sgr A*. These results distinguish disk-regulating magnetic torques from black-hole-sourced jet transport and show how flux eruptions couple disk accretion, winds, and jet morphology.
Related
- Magnetized accretion onto rapidly spinning binary black holes: mini-disk thermodynamics, magnetic transport, and dual jets
- Three-dimensional simulations of accretion disks in pre-CE systems -- II. Accretion efficiency and angular momentum transport
- Magnetized Accretion Flows with Low Angular Momentum Around Supermassive Black Holes
- Low-angular-momentum Accretion Shocks Can Power Weak-to-moderate X-Ray Flares from Sgr A*
- Low-angular-momentum accretion shocks can power weak-to-moderate X-ray flares from SgrA*
BibTeX
@misc{raha2026angular,
title = {{Angular Momentum Transport across Accretion States around a rapidly spinning black hole}},
author = {Rohan Raha and Koushik Chatterjee},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.01827},
eprint = {2611.01827},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.01827},
}
RIS
TY - UNPB
TI - Angular Momentum Transport across Accretion States around a rapidly spinning black hole
AU - Rohan Raha
AU - Koushik Chatterjee
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.01827
UR - https://arxiv.org/abs/2611.01827
AB - Accretion requires the outward transport of angular momentum, but the relative contributions of matter advection, turbulent stresses, ordered magnetic fields, winds, and black-hole spin remain uncertain in strongly magnetized flows. We use high-resolution three-dimensional GRMHD simulations around a rapidly rotating black hole (a=0.998) to compare SANE, intermediate-flux, and magnetically arrested disk states. In SANE and intermediate states, outward stresses are insufficient to overcome inward angular-momentum advection, and the net flux remains inward. In MAD, ordered Maxwell stresses regulate the disk and drive winds, while the Blandford-Znajek jet carries a distinct, near-constant flux extracted from the black hole, making the total angular-momentum flux outward. Magnetic-flux eruptions modulate both channels. During an eruption, an equatorial current sheet extends beyond the ergosphere, and low-density, magnetically dominated bubbles of expelled flux enter the polar region. The jet becomes asymmetric, its tilt more than doubles, and its opening angle first widens and then contracts below its pre-eruption value. Eruptions suppress the horizon accretion rate and briefly reverse the angular-momentum flux through the jet surface, while reorganizing the Maxwell stresses in the disk. As horizon-threading flux re-accumulates, the turbulent stress recovers toward its saturated MAD level. Eruption durations and lags among horizon flux, accretion rate, and jet tilt of ~40-90 r_g/c correspond to milliseconds for stellar-mass black holes and tens of minutes for Sgr A*. These results distinguish disk-regulating magnetic torques from black-hole-sourced jet transport and show how flux eruptions couple disk accretion, winds, and jet morphology.
ER -