http://arxiv.org/abs/1803.03278
We have modeled direct collapse of a primordial gas within dark matter halos in the presence of radiative transfer. High-resolution zoom-in numerical simulations of gravitational collapse have been performed in a cosmological framework, down to the formation of the photosphere and growth of the central object. Radiative transfer has been implemented in the flux-limited diffusion (FLD) approximation, and adiabatic models have been run for comparison. We find that (1) the FLD flow forms an irregular central structure with dynamically insignificant rotation, and does not exhibit fragmentation. This is contrary to adiabatic flow which forms an asymmetric, geometrically-thick disk that drives a pair of strong spiral shocks, subject to Kelvin-Helmholtz shear instability, forming fragments, which tend to merge with the central disk; (2) the growing central core in the FLD flow quickly reaches a core mass of ~10 Mo and a highly variable luminosity of order of 10^38-10^39 erg/s, comparable to the Eddington luminosity. It experiences massive recurrent outflows driven by radiation force and thermal pressure gradients, which form dense expanding shells, mixing with the accretion flow and transferring the angular momentum outwards; and (3) the interplay between radiation and thermal pressure gradients and gravity, subject to the massive accretion rate, results in photosphere of radius ~10 AU, much larger than that of a protostar. Overall, the inclusion of radiative transfer reveals complex early stages of formation and growth of the central structure in direct collapse scenario of massive black hole formation.
K. Ardaneh, Y. Luo, I. Shlosman et. al.
Mon, 12 Mar 2018
5/45
Comments: 19 pages, 16 figures, submitted to MNRAS