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arXiv · 2511.08668

Bridging scales: How much do supermassive black holes grow in the suppressed Bondi regime?

Kung-Yi Su·Angelo Ricarte·Priyamvada Natarajan·Antonio J. Porras-Valverde·Hyerin Cho·Ramesh Narayan·Claude-André Faucher-Giguère·Philip F. Hopkins·Ben S. Prather
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Abstract

The co-evolution of supermassive black holes (SMBHs) and their host galaxies remains one of the central open questions in cosmology, rooted in the coupling between accretion, feedback, and the multi-scale physics that links the event horizon to the circumgalactic medium. Here we bridge these scales by embedding a first-principles, GRMHD-informed prescription for black hole accretion and feedback--derived from multi-zone simulations that self-consistently connect inflows and outflows from the horizon to the Bondi radius--within cosmological magnetohydrodynamic zoom-in simulations of $\sim10^{14}\,M_\odot$ halos. These GRMHD results predict a "suppressed Bondi" regime in which magnetic stresses and relativistic winds strongly reduce effective accretion rates in a spin-dependent manner. We find that black holes cannot grow efficiently by accretion until they exceed $\sim10^{7}\,M_\odot$, regardless of the feedback strength. Beyond this threshold, systems bifurcate: low-spin ($\eta\!\sim\!0.02$) black holes continue to accrete without quenching star formation, while high-spin ($\eta\!\gtrsim\!0.3$) black holes quench effectively but become starved of further growth. Early, massive seeding partially alleviates this tension through merger-driven assembly, yet an additional cold or super-Eddington accretion mode appears essential to reproduce the observed SMBH population and the empirical black hole--galaxy scaling relations. Our results demonstrate that GRMHD-informed feedback models can account for the maintenance-mode behavior of low-luminosity AGN like M87*, but cannot by themselves explain the full buildup of SMBH mass across cosmic time. A unified, multi-regime framework is required to capture the evolving interplay between spin-dependent feedback, cold inflows, and mergers in driving co-evolution.

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Kung-Yi Su, Angelo Ricarte, Priyamvada Natarajan, Antonio J. Porras-Valverde, Hyerin Cho, Ramesh Narayan, Claude-André Faucher-Giguère, Philip F. Hopkins, Ben S. Prather. 2025-11-11. Bridging scales: How much do supermassive black holes grow in the suppressed Bondi regime?. https://arxiv.org/abs/2511.08668

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