Formation of an embryonic supermassive star in the first galaxy

Understand

We studied the gravitational collapse of a warm (~8000 K) primordial-gas cloud as a candidate progenitor for a supermassive star (SMS; >10^5 Msun) using a three-dimensional hydrodynamical simulation, including all the relevant cooling processes of both H_2 and H, which can potentially induce cloud fragmentation.

• This is the first simulation of this kind to resolve protostar formation.
• We find that the cloud undergoes runaway collapse without a major episode of fragmentation.
• Although the H_2 fraction jumps by a large factor via the three-body reaction at ~10^-13 g/cm^3, its cooling remains inefficient due to the optical thickness, and the temperature remains >3000 K.