# Rapid Formation of Massive Black Holes in close proximity to Embryonic Proto-Galaxies

## TL;DR

This paper demonstrates through high-resolution simulations that synchronized radiation from neighboring proto-galaxies can rapidly induce the formation of massive black holes via direct collapse in the early universe.

## Contribution

It introduces a novel mechanism showing how synchronized LW radiation from neighboring proto-galaxies triggers direct collapse black hole formation.

## Key findings

- Low-level background LW flux combined with synchronized irradiation leads to atomic cooling.
- This process results in proto-galaxies forming massive black holes of 10^4 - 10^5 solar masses.
- The mechanism avoids gas photo-evaporation and heavy element pollution.

## Abstract

The Direct Collapse Black Hole (DCBH) scenario provides a solution for forming the massive black holes powering bright quasars observed in the early Universe. A prerequisite for forming a DCBH is that the formation of (much less massive) Population III stars be avoided - this can be achieved by destroying H$_2$ via Lyman-Werner (LW) radiation (E$_{\rm{LW}}$ = 12.6 eV). We find that two conditions must be met in the proto-galaxy that will host the DCBH. First, prior star formation must be delayed; this can be achieved with a background LW flux of J$_{\rm BG} \gtrsim 100\ J_{21}$. Second, an intense burst of LW radiation from a neighbouring star-bursting proto-galaxy is required, just before the gas cloud undergoes gravitational collapse, to finally suppress star formation completely. We show here for the first time using high-resolution hydrodynamical simulations, including full radiative transfer, that this low-level background, combined with tight synchronisation and irradiation of a secondary proto-galaxy by a primary proto-galaxy, inevitably moves the secondary proto-galaxy onto the isothermal atomic cooling track, without the deleterious effects of either photo-evaporating the gas or polluting it by heavy elements. These, atomically cooled, massive proto-galaxies are expected to ultimately form a DCBH of mass $10^4 - 10^5 M_{\odot}$.