講演者名:竹尾英俊

タイトル:Super-Eddington growth of black holes exposed to anisotropic radiation

アブスト: We perform two-dimensional radiation hydrodynamical simulations of accretion flows onto a black hole (BH) in order to study rapid growth of BHs in the early Universe. For spherically symmetric flows, hyper-Eddington accretion onto the BH from outside the Bondi radius can occur unimpeded by radiation feedback only when the BH mass is higher than 10,000Msun. Here, we study the properties of accretion flows exposed to anisotropic radiation from a nuclear accretion disk with a luminosity higher than the Eddington value due to collimation toward the bipolar directions. We find that even less massive BHs with < 10,000Msun can be fed by surrounding gas at high accretion rates through the equatorial plane. For more massive BHs with M > 500,000Msun, neutral gas through the equatorial plane totally covers the central radiating region due to the non-radial gas motions, and thus the emergent radiation in all directions is blocked. Because of efficient recombination by hydrogen, the entire flow results in neutral and warm gas with 8000 K. Moreover, radiation momentum absorbed by neutral hydrogen produces warm outflows toward the bipolar directions at ~30 % of the BH feeding rate and with a typical velocity of 50 km/s.