Direct Collapse to Precursors of Supermassive Black Hole Seeds:Radiation-feedback-generated Outflows

Abstract

We use high-resolution zoom-in cosmological simulations to model outflow triggered by radiation and thermal drivers around the central mass accumulation during direct collapse within the dark matter (DM) halo. The maximal resolution is $1.3\times 10^{-5}$\,pc, and no restrictions are put on the geometry of the inflow/outflow. The central mass is considered {\it prior} to the formation of the supermassive black hole seed at a redshift of $z\sim 15.9$, and can constitute either a supermassive star (SMS) of $\sim 10^5{M}_{\odot }$ surrounded by a growing accretion disk or a self-gravitating disk. The radiation transfer is modeled using the ray-tracing algorithm. Due to the high accretion rate of $\sim 1M_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$ determined by the DM halo, accretion is mildly supercritical, resulting in mildly super-critical luminosity which has only a limited effect on the accretion rate, with the duty cycle of $\sim 0.9$. We observe a fast development of hot cavities, which quickly extend into polar funnels and expand dense shells. Within the funnels, fast winds, $\sim 10^3\mathrm{km}{\mathrm{s}}^{-1}$, are mass-loaded by the accreting gas. We follow the expanding shells to $\sim 1$\,pc, when the shell velocity remains substantially, $\sim 5$ times, above the escape speed. The ionization cones formed by the central UV/X-ray completely ionize the cavities. Extrapolating the outflow properties shows that the halo material outside the shell will have difficulty stopping it. We therefore conclude that the expanding wind-driven shell will break out of the central parsec and will reach the halo virial radius. Finally, the anisotropic accretion flow on sub-parsec scales will attenuate the UV/soft X-rays on the H${}_2$. Hence, the formation of funnels and powerful outflows around, e.g., SMS, can have interesting observational corollaries.

20 pages, 12 figures, submitted to ApJ. Accepted for publication in ApJ