Enhanced direct collapse due to Lyman α feedback

We assess the impact of trapped Lyman α cooling radiation on the formation of direct collapse black holes (DCBHs). We apply a one-zone chemical and thermal evolution model, accounting for the photodetachment of H− ions, precursors to the key coolant H2, by Lyman α photons produced during the collaps...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2017-05, Vol.601, p.A138
Main Authors: Johnson, Jarrett L., Dijkstra, Mark
Format: Article
Language:English
Subjects:
Background radiation
black hole physics
Black holes
Collapse
Cooling
cosmology: theory
dark ages
first stars
Galaxies
Hot stars
molecular processes
Organic chemistry
Photodetachment
Photons
Quasars
quasars: supermassive black holes
Radiation
radiative transfer
Red shift
reionization
Seeds
Thermal evolution
Universe
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Summary:We assess the impact of trapped Lyman α cooling radiation on the formation of direct collapse black holes (DCBHs). We apply a one-zone chemical and thermal evolution model, accounting for the photodetachment of H− ions, precursors to the key coolant H2, by Lyman α photons produced during the collapse of a cloud of primordial gas in an atomic cooling halo at high redshift. We find that photodetachment of H− by trapped Lyman α photons may lower the level of the H2-dissociating background radiation field required for DCBH formation substantially, dropping the critical flux by up to a factor of a few. This translates into a potentially large increase in the expected number density of DCBHs in the early Universe, and supports the view that DCBHs may be the seeds for the BHs residing in the centers of a significant fraction of galaxies today. We find that detachment of H− by Lyman α has the strongest impact on the critical flux for the relatively high background radiation temperatures expected to characterize the emission from young, hot stars in the early Universe. This lends support to the DCBH origin of the highest redshift quasars.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/201630010