Suppression of H2-cooling in protogalaxies aided by trapped Lyα cooling radiation. Issue 1 (9th October 2020)

• Record Type: Journal Article
• Authors: Wolcott-Green, Jemma; Haiman, Zoltán; Bryan, Greg L
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 1(2021)
• Page Start: 138
• Page End: 144
• Publication Date: 2020-10-09
• Subjects: molecular processes -- stars: Population III -- galaxies: formation -- cosmology: theory -- early Universe; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3057
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 α cooling radiation trapped in the optically-thick cores of three such haloes, a process that has not been included in previous simulations. Because H − is a precursor of molecular hydrogen, its destruction can diminish the H2 abundance and cooling. We find that the critical UV flux for suppressing H2 -cooling is decreased by ∼15–50 per cent in our fiducial models. Previous one-zone modelling found a larger effect, with J crit reduced by a factor of a few; we show that adopting a constant halo mass to determine the trapped Ly α energy density, as is done in the one-zone models, yields a larger reduction in J crit, consistent with their findings. Our results nevertheless suggest that Ly α radiation may have an important effect on the thermal evolution of UV-irradiated haloes, and therefore on the potential for massive black hole formation.