Suppression of H2-cooling in protogalaxies aided by trapped Ly{alpha} cooling radiation. (arXiv:2001.05498v1 [astro-ph.GA])

Suppression of H2-cooling in protogalaxies aided by trapped Ly{alpha} cooling radiation. (arXiv:2001.05498v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wolcott_Green_J/0/1/0/all/0/1">Jemma Wolcott-Green</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haiman_Z/0/1/0/all/0/1">Zoltan Haiman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bryan_G/0/1/0/all/0/1">Greg L. Bryan</a>

We study the thermal evolution of UV-irradiated atomic cooling haloes using
high-resolution three-dimensional hydrodynamic simulations. We consider the
effect of H^- photodetachment by Ly{alpha} cooling radiation trapped in the
optically-thick cores of three such haloes, a process which has not been
included in previous simulations. H^- is a precursor of molecular hydrogen, and
therefore, its destruction can diminish the H2 abundance and cooling. Using a
simple high-end estimate for the trapped Ly{alpha} energy density, we find
that H^- photodetachment by Ly{alpha} decreases the critical UV flux for
suppressing H2-cooling by up to a factor of approx 5. With a more conservative
estimate of the Ly{alpha} energy density, we find the critical flux is
decreased only by ~15-50 percent. Our results suggest that Ly{alpha} radiation
may have an important effect on the thermal evolution of UV-irradiated haloes,
and therefore on the potential for massive black hole formation.

We study the thermal evolution of UV-irradiated atomic cooling haloes using
high-resolution three-dimensional hydrodynamic simulations. We consider the
effect of H^- photodetachment by Ly{alpha} cooling radiation trapped in the
optically-thick cores of three such haloes, a process which has not been
included in previous simulations. H^- is a precursor of molecular hydrogen, and
therefore, its destruction can diminish the H2 abundance and cooling. Using a
simple high-end estimate for the trapped Ly{alpha} energy density, we find
that H^- photodetachment by Ly{alpha} decreases the critical UV flux for
suppressing H2-cooling by up to a factor of approx 5. With a more conservative
estimate of the Ly{alpha} energy density, we find the critical flux is
decreased only by ~15-50 percent. Our results suggest that Ly{alpha} radiation
may have an important effect on the thermal evolution of UV-irradiated haloes,
and therefore on the potential for massive black hole formation.

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