Radiation–hydrodynamical collapse of pre-galactic clouds in the ultraviolet background |
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| Authors: | T Kitayama Y Tajiri M Umemura H Susa S Ikeuchi |
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| Institution: | Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan;Institute of Physics, University of Tsukuba, Tsukuba 305-8577, Japan;Center for Computational Physics, University of Tsukuba, Tsukuba 305-8577, Japan;Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan |
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| Abstract: | To explain the effects of the ultraviolet (UV) background radiation on the collapse of pre-galactic clouds, we implement a radiation–hydrodynamical calculation, combining one-dimensional spherical hydrodynamics with an accurate treatment of the radiative transfer of ionizing photons. Both absorption and scattering of UV photons are explicitly taken into account. It turns out that a gas cloud contracting within the dark matter potential does not settle into hydrostatic equilibrium, but undergoes run-away collapse even under the presence of the external UV field. The cloud centre is shown to become self-shielded against ionizing photons by radiative transfer effects before shrinking to the rotation barrier. Based on our simulation results, we further discuss the possibility of H2 cooling and subsequent star formation in a run-away collapsing core. The present results are closely relevant to the survival of subgalactic Population III objects as well as to metal injection into intergalactic space. |
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| Keywords: | radiative transfer galaxies: formation cosmology: theory diffuse radiation |
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