Suppression of H2-cooling in protogalaxies aided by trapped Lyα cooling radiation
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 Lyα 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 Jcrit reduced by a factor of a few; we show that adopting a constant halo mass to determine the trapped Lyα energy density, as is done in the one-zone models, yields a larger reduction in Jcrit, consistent with their findings. Our results nevertheless suggest that Lyα radiation may have an important effect on the thermal evolution of UV-irradiated haloes, and therefore on the potential for massive black hole formation.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2021
- DOI:
- 10.1093/mnras/staa3057
- arXiv:
- arXiv:2001.05498
- Bibcode:
- 2021MNRAS.500..138W
- Keywords:
-
- molecular processes;
- stars: Population III;
- galaxies: formation;
- cosmology: theory;
- early Universe;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 8 pages, 5 figures