http://arxiv.org/abs/1711.07315
We perform a set of cosmological simulations of early structure formation with incorporating baryonic streaming motions. We present a case where a significantly elongated gas cloud with $\sim!10^4\,$solar-masses (${\rm M_\odot}$) is formed in a pre-galactic ($\sim!10^7\,{\rm M_\odot}$) dark halo. The gas streaming into the halo compresses and heats the massive filamentary cloud to a temperature of $\sim!10000\,$Kelvin. The gas cloud cools rapidly by atomic hydrogen cooling and then by molecular hydrogen cooling down to $\sim!400\,$Kelvin. The rapid decrease of the temperature and hence of the Jeans mass triggers fragmentation of the filament to yield multiple gas clumps with a few hundred solar-masses. We estimate the mass of the primordial star formed in each fragment by adopting an analytic model based on a large set of radiation hydrodynamics simulations of protostellar evolution. The resulting stellar masses are in the range of $\sim!50$–$120\,{\rm M_\odot}$. The massive stars gravitationally attract each other and form a compact star cluster. We follow the dynamics of the star cluster using a hybrid $N$-body simulation. We show that massive star binaries are formed in a few million years through multi-body interactions at the cluster center. Eventual formation of the remnant black holes will leave a massive black hole binary, which can be a progenitor of strong gravitational wave sources similar to those recently detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).
S. Hirano, N. Yoshida, Y. Sakurai, et. al.
Tue, 21 Nov 17
38/79
Comments: 13 pages, 11 figures, 2 tables