Sowing black hole seeds: Direct collapse black hole formation with realistic Lyman-Werner radiation in cosmological simulations

Glenna Dunn; Jillian Bellovary; Kelly Holley-Bockelmann; Charlotte Christensen; Thomas Quinn

doi:10.3847/1538-4357/aac7c2

paper

Sowing black hole seeds: Direct collapse black hole formation with realistic Lyman-Werner radiation in cosmological simulations

arXiv:1803.01007 · doi:10.3847/1538-4357/aac7c2

Abstract

We study the birth of supermassive black holes from the direct collapse process and characterize the sites where these black hole seeds form. In the pre-reionization epoch, molecular hydrogen (H $_{2}$ ) is an efficient coolant, causing gas to fragment and form Population III stars, but Lyman-Werner radiation can suppress H $_{2}$ formation and allow gas to collapse directly into a massive black hole. The critical flux required to inhibit H $_{2}$ formation, $J_{crit}$ , is hotly debated, largely due to the uncertainties in the source radiation spectrum, H $_{2}$ self-shielding, and collisional dissociation rates. Here, we test the power of the direct collapse model in a self-consistent, time-dependant, non-uniform Lyman-Werner radiation field -- the first time such has been done in a cosmological volume -- using an updated version of the SPH+N-body tree code Gasoline with H $_{2}$ non-equilibrium abundance tracking, H $_{2}$ cooling, and a modern SPH implementation. We vary $J_{crit}$ from $30$ to $1 0^{3}$ in units of $J_{21}$ to study how this parameter impacts the number of seed black holes and the type of galaxies which host them. We focus on black hole formation as a function of environment, halo mass, metallicity, and proximity of the Lyman-Werner source. Massive black hole seeds form more abundantly with lower $J_{crit}$ thresholds, but regardless of $J_{crit}$ , these seeds typically form in halos that have recently begun star formation. Our results do not confirm the proposed atomic cooling halo pair scenario; rather black hole seeds predominantly form in low-metallicity pockets of halos which already host star formation.

arXiv comment10 pages, 8 figures, accepted by ApJ

Sowing black hole seeds: Direct collapse black hole formation with realistic Lyman-Werner radiation in cosmological simulations

Abstract

References in corpus (111)

Cited by in corpus (22)