Bridging Scales: Multi-Zone GRMHD-Informed Anisotropic AGN Feedback in Galaxies
Abstract
We present a galaxy-scale black hole (BH) accretion and feedback model incorporating results from multi-zone general relativistic magnetohydrodynamic (GRMHD) simulations spanning the event horizon to the Bondi radius. The model replaces a fixed suppression of the Bondi rate with a nuclear-environment-dependent factor, κhotcho, set by the local ratio of Bondi to gravitational radius, and distributes outflow mass, kinetic energy, and thermal energy according to the angular structure measured in the large-dynamic-range GRMHD calculations. We apply it to idealized isolated simulations of an M87*-like massive elliptical and a Milky Way/Sgr A*-like galaxy, spanning over three orders of magnitude in BH mass without tuning accretion or feedback efficiencies to match observables. In the M87*-like system, the GRMHD-informed angle-dependent feedback model suppresses late-time stellar mass growth more effectively than the isotropic reference model, despite similar long-term BH accretion rates. Varying the uncertain mass loading of the collimated polar component has a modest impact on BH growth and star formation, indicating that feedback anisotropy matters more than its detailed mass loading. We find that κhotcho varies with nuclear environment and time, yielding BH growth histories markedly different from fixed-suppression models. For Sgr A*, this variable factor yields an accretion rate more consistent with Event Horizon Telescope (EHT) constraints than a fixed, suppressed Bondi model. These results show that nuclear-environment-dependent accretion and feedback angular structure affect BH-galaxy evolution, requiring subgrid models to include more than a universal Bondi suppression factor and a scalar feedback efficiency.
Related
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BibTeX
@misc{su2026bridging,
title = {{Bridging Scales: Multi-Zone GRMHD-Informed Anisotropic AGN Feedback in Galaxies}},
author = {Kung-Yi Su and Hyerin Cho and Priyamvada Natarajan and Claude-André Faucher-Giguère and Ramesh Narayan and Angelo Ricarte and Antonio J. Porras-Valverde and Cora Prather and Philip F. Hopkins},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40784},
eprint = {2610.40784},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40784},
}
RIS
TY - UNPB
TI - Bridging Scales: Multi-Zone GRMHD-Informed Anisotropic AGN Feedback in Galaxies
AU - Kung-Yi Su
AU - Hyerin Cho
AU - Priyamvada Natarajan
AU - Claude-André Faucher-Giguère
AU - Ramesh Narayan
AU - Angelo Ricarte
AU - Antonio J. Porras-Valverde
AU - Cora Prather
AU - Philip F. Hopkins
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40784
UR - https://arxiv.org/abs/2610.40784
AB - We present a galaxy-scale black hole (BH) accretion and feedback model incorporating results from multi-zone general relativistic magnetohydrodynamic (GRMHD) simulations spanning the event horizon to the Bondi radius. The model replaces a fixed suppression of the Bondi rate with a nuclear-environment-dependent factor, κ^hot_cho, set by the local ratio of Bondi to gravitational radius, and distributes outflow mass, kinetic energy, and thermal energy according to the angular structure measured in the large-dynamic-range GRMHD calculations. We apply it to idealized isolated simulations of an M87*-like massive elliptical and a Milky Way/Sgr A*-like galaxy, spanning over three orders of magnitude in BH mass without tuning accretion or feedback efficiencies to match observables. In the M87*-like system, the GRMHD-informed angle-dependent feedback model suppresses late-time stellar mass growth more effectively than the isotropic reference model, despite similar long-term BH accretion rates. Varying the uncertain mass loading of the collimated polar component has a modest impact on BH growth and star formation, indicating that feedback anisotropy matters more than its detailed mass loading. We find that κ^hot_cho varies with nuclear environment and time, yielding BH growth histories markedly different from fixed-suppression models. For Sgr A*, this variable factor yields an accretion rate more consistent with Event Horizon Telescope (EHT) constraints than a fixed, suppressed Bondi model. These results show that nuclear-environment-dependent accretion and feedback angular structure affect BH-galaxy evolution, requiring subgrid models to include more than a universal Bondi suppression factor and a scalar feedback efficiency.
ER -