We investigate the environment in which direct-collapse black holes may form by analysing a cosmological , hydrodynamical simulation that is part of the First Billion Years project .
This simulation includes the most relevant physical processes leading to direct collapse of haloes , most importantly , molecular hydrogen depletion by dissociation of H _ { 2 } and H ^ { - } from the evolving Lyman-Werner radiation field .
We selected a sample of pristine atomic cooling haloes that have never formed stars in their past , have not been polluted with heavy elements and are cooling predominantly via atomic hydrogen lines .
Amongst them we identified six haloes that could potentially harbour massive seed black holes formed via direct collapse ( with masses in the range of 10 ^ { 4 - 6 } ~ { } \mathrm { M } _ { \odot } ) .
These potential hosts of direct-collapse black holes form as satellites are found within 15 physical kpc of proto-galaxies , with stellar masses in the range \approx 10 ^ { 5 - 7 } ~ { } \mathrm { M } _ { \odot } and maximal star formation rates of \approx 0.1 ~ { } \mathrm { M } _ { \odot } \mathrm { yr } ^ { -1 } over the past 5 ~ { } \mathrm { Myr } , and are exposed to the highest flux of Lyman-Werner radiation emitted from the neighbouring galaxies .
It is the proximity to these proto-galaxies that differentiates these haloes from rest of the sample .