Simulating the formation of massive seed black holes in the early Universe. III: The influence of X-rays

Understand

The direct collapse black hole (DCBH) model attempts to explain the observed number density of supermassive black holes in the early Universe by positing that they grew from seed black holes with masses of $10^{4}$-$10^{5} \: {\rm M_{\odot}}$ that formed by the quasi-isothermal collapse of gas in metal-free protogalaxies cooled by atomic hydrogen emission.

• For this model to work, H$_{2}$ formation must be suppressed in at least some of these systems by a strong extragalactic radiation field.
• The predicted number density of DCBH seeds is highly sensitive to the minimum value of the ultraviolet (UV) flux required to suppress H$_{2}$ formation, $J_{\rm crit}$.
• In this paper, we examine how the value of $J_{\rm crit}$ varies as we vary the strength of a hypothetical high-redshift X-ray background.