http://arxiv.org/abs/1611.00780
We assess the impact of trapped Lyman {\alpha} 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 H$_{\rm 2}$, by Lyman {\alpha} 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 {\alpha} photons can lower the level of the H$_{\rm 2}$-dissociating background radiation field required for DCBH formation substantially, dropping the critical flux by up to an order of magnitude. This translates into a large increase in the expected number density of DCBHs in the early Universe, and implies 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 {\alpha} 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.
J. Johnson and M. Dijkstra
Fri, 4 Nov 16
18/58
Comments: 5 pages, 4 figures, 1 table; to be submitted to A&A