# Formation of massive black holes in rapidly growing pre-galactic gas clouds

## TL;DR

This study uses radiation hydrodynamics simulations to demonstrate that rapid growth in metal-free early Universe haloes can naturally lead to the formation of supermassive stars, which are potential seeds for supermassive black holes, emphasizing structure formation dynamics over LW flux.

## Contribution

It shows that structure formation dynamics, especially rapid halo growth, are key to massive black hole seed formation, challenging the emphasis on critical Lyman-Werner flux levels.

## Key findings

- Rapid halo growth induces conditions for supermassive star formation.
- Massive black hole seeds could be more common in overdense early regions.
- Formation of SMBH seeds is driven by structure dynamics, not just LW flux.

## Abstract

The origin of supermassive black holes (SMBHs) that inhabit the centers of massive galaxies is largely unconstrained. Remnants from supermassive stars (SMSs) with masses around 10,000 solar masses provide the ideal seed candidates, known as direct collapse black holes. However, their very existence and formation environment in the early Universe are still under debate, with their supposed rarity further exacerbating the problem of modeling their ab-initio formation. SMS models have shown that rapid collapse, with an infall rate above a critical value, in metal-free haloes is a requirement for the formation of a proto-stellar core which will then form an SMS. Using a radiation hydrodynamics simulation of early galaxy formation, we show the natural emergence of metal-free haloes both massive enough, and with sufficiently high infall rates, to form an SMS. We find that haloes that are exposed to both a Lyman-Werner intensity of J_LW ~ 3 J_21 and that undergo at least one period of rapid growth early in their evolution are ideal cradles for SMS formation. This rapid growth induces substantial dynamical heating, amplifying the existing Lyman-Werner suppression originating from a group of young galaxies 20 kiloparsecs away. Our results strongly indicate that structure formation dynamics, rather than a critical Lyman-Werner (LW) flux, may be the main driver of massive black hole formation in the early Universe. We find that massive black hole seeds may be much more common in overdense regions of the early Universe than previously considered with a comoving number density up to 10^-3 Mpc^-3.