Supermassive Black Hole Formation at High Redshifts via Direct Collapse in a Cosmological Context

Authors

Jun-Hwan Choi, University of Texas - Austin
Isaac Shlosman, University of KentuckyFollow
Mitchell C. Begelman, University of Colorado

Abstract

We study the early stage of the formation of seed supermassive black holes via direct collapse in dark matter (DM) haloes, in the cosmological context. We perform high-resolution zoom-in simulations of such collapse at high z. Using the adaptive mesh refinement code enzo, we resolve the formation and growth of a DM halo, until its virial temperature reaches ∼10⁴ K, atomic cooling turns on, and collapse ensues. We demonstrate that direct collapse proceeds in two stages, although they are not well separated. The first stage is triggered by the onset of atomic cooling, and leads to rapidly increasing accretion rate with radius, from Ṁ~0.1M_⊙yr⁻¹ at the halo virial radius to few M_⊙ yr⁻¹, around the scale radius R_s ∼ 30 pc of the NFW DM density profile. The second stage of the collapse commences when the gas density takes precedence over the DM density. This is associated with the gas decoupling from the DM gravitational potential. The ensuing collapse approximates that of an isothermal sphere with Ṁ(r) ~ const. We confirm that the gas loses its angular momentum through non-axisymmetric perturbations and gravitational torques, to overcome the centrifugal barrier. During the course of the collapse, this angular momentum transfer process happens on nearly all spatial scales, and the angular momentum vector of the gas varies with position and time. Collapsing gas also exhibits supersonic turbulent motions which suppress gas fragmentation, and are characterized by density PDF consisting of a lognormal part and a high-density power-law tail.

Document Type

Article

Publication Date

7-11-2015

Notes/Citation Information

Published in Monthly Notices of the Royal Astronomical Society, v. 450, no. 4, p. 4411-4423.

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1093/mnras/stv694

Funding Information

JHC acknowledges support from NASA ATP NNX11AE09G, NSF AST-1009799, and Caltech/JPL SURP Project No. 1515294. through The University of Texas at Austin (P.I. Paul Shapiro). IS acknowledges support from NSF grant AST-0807760, from HST/STScI grant AR-12639.01-A, and from International Joint Research Promotion Program at Osaka University. MCB acknowledges support from the NSF under AST-0907872. Support for HST/STScI AR-12639.01-A was provided by NASA through a grant from the STScI, which is operated by the AURA, Inc., under NASA contract NAS5-26555.

Repository Citation

Choi, Jun-Hwan; Shlosman, Isaac; and Begelman, Mitchell C., "Supermassive Black Hole Formation at High Redshifts via Direct Collapse in a Cosmological Context" (2015). Physics and Astronomy Faculty Publications. 276.
https://uknowledge.uky.edu/physastron_facpub/276