Hyper-Eddington Black Hole Growth in Star-Forming Molecular Clouds and Galactic Nuclei: Can It Happen?
Abstract
Formation of supermassive black holes (BHs) remains a theoretical challenge. In many models, especially beginning from stellar relic "seeds," this requires sustained super-Eddington accretion. While studies have shown BHs can violate the Eddington limit on accretion disk scales given sufficient "fueling" from larger scales, what remains unclear is whether or not BHs can actually capture sufficient gas from their surrounding ISM. We explore this in a suite of multi-physics high-resolution simulations of BH growth in magnetized, star-forming dense gas complexes including dynamical stellar feedback from radiation, stellar mass-loss, and supernovae, exploring populations of seeds with masses ∼1−10⁴ M_⊙. In this initial study, we neglect feedback from the BHs: so this sets a strong upper limit to the accretion rates seeds can sustain. We show that stellar feedback plays a key role. Complexes with gravitational pressure/surface density below ∼10³ M_⊙ pc⁻² are disrupted with low star formation efficiencies so provide poor environments for BH growth. But in denser cloud complexes, early stellar feedback does not rapidly destroy the clouds but does generate strong shocks and dense clumps, allowing ∼1% of randomly-initialized seeds to encounter a dense clump with low relative velocity and produce runaway, hyper-Eddington accretion (growing by orders of magnitude). Remarkably, mass growth under these conditions is almost independent of initial BH mass, allowing rapid IMBH formation even for stellar-mass seeds. This defines a necessary (but perhaps not sufficient) set of criteria for runaway BH growth: we provide analytic estimates for the probability of runaway growth under different ISM conditions.
Additional Information
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). We thank Xiangcheng Ma and Linhao Ma for useful discussions and revisions of this draft. Support for the authors was provided by NSF Research Grants 1911233, 20009234, 2108318, NSF CAREER grant 1455342, NASA grants 80NSSC18K0562, HST-AR-15800. Numerical calculations were run on the Caltech compute cluster "Wheeler," allocations AST21010 and AST20016 supported by the NSF and TACC, and NASA HEC SMD-16-7592. DATA AVAILABILITY STATEMENT. The data supporting the plots within this article are available on reasonable request to the corresponding author. A public version of the GIZMO code is available at http://www.tapir.caltech.edu/~phopkins/Site/GIZMO.html.Attached Files
Submitted - 2208.05025.pdf
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Additional details
- Eprint ID
- 116328
- Resolver ID
- CaltechAUTHORS:20220816-221958140
- AST-1911233
- NSF
- AST-20009234
- NSF
- AST-2108318
- NSF
- AST-1455342
- NSF
- 80NSSC18K0562
- NASA
- HST-AR-15800
- NASA
- AST-21010
- NSF
- AST-20016
- NSF
- Texas Advanced Computing Center (TACC)
- SMD-16-7592
- NASA
- Created
-
2022-08-18Created from EPrint's datestamp field
- Updated
-
2023-06-02Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, TAPIR