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The effects of metallicity and cooling physics on fragmentation: implications on direct-collapse black hole formation

Moran, C. Corbett and Grudić, M. Y. and Hopkins, P. F. (2018) The effects of metallicity and cooling physics on fragmentation: implications on direct-collapse black hole formation. . (Unpublished)

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A promising supermassive black hole seed formation channel is that of direct collapse from primordial gas clouds. We perform a suite of 3D hydrodynamics simulations of an isolated turbulent gas cloud to investigate conditions conducive to forming massive black hole seeds via direct collapse, probing the impact of cloud metallicity, gas temperature floor and cooling physics on cloud fragmentation. We find there is no threshold in metallicity which produces a sharp drop in fragmentation. When molecular cooling is not present, metallicity has little effect on fragmentation. When molecular cooling is present, fragmentation is suppressed by at most ∼25%, with the greatest suppression seen at metallicities below 2% solar. A gas temperature floor ∼10^4 K produces the largest drop in fragmentation of any parameter choice, reducing fragmentation by ∼60%. At metallicities below 2% solar or at temperatures ∼10^3 K we see a reduction in fragmentation ∼20−25%. For a cloud of metallicity 2% solar above and a temperature below 10^3 K, the detailed choices of temperature floor, metallicity, and cooling physics have little impact on fragmentation.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Moran, C. Corbett0000-0003-2088-7465
Hopkins, P. F.0000-0003-3729-1684
Additional Information:CCM was supported by the NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1501208. Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NSF Collaborative Research Grant #1715847 and CAREER grant #1455342. Numerical calculations were run on the Caltech compute cluster "Wheeler," allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
NSF Astronomy and Astrophysics FellowshipAST-1501208
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:hydrodynamics - galaxies: star formation - stars: massive - methods: numerical - galaxies: star formation : general
Record Number:CaltechAUTHORS:20190206-105545425
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92715
Deposited By: George Porter
Deposited On:08 Feb 2019 20:43
Last Modified:09 Mar 2020 13:18

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