2007/11/30 by Jarrett L. Johnson, Thomas H. Greif, Volker Bromm · 104 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Electrical and Electromagnetic Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Population #Redshift #Star formation #Stars #Stellar mass #Universe #Virial theorem #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13381.x
published in Monthly Notices of the Royal Astronomical Society 388(1), 26-38 (Oxford University Press) · 13 pages, 5 figures; now accepted to MNRAS
arxiv created 2008/04/23 · openalex publication_date 2008/06/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The character of the first galaxies at redshifts z≳ 10 strongly depends on their level of pre-enrichment, which is in turn determined by the rate of primordial star formation prior to their assembly. In order for the first galaxies to remain metal-free, star formation in minihaloes must be highly suppressed, most likely by H2-dissociating Lyman–Werner (LW) radiation. We show that the build-up of such a strong LW background is hindered by two effects. First, the level of the LW background is self-regulated, being produced by the Population III (Pop III) star formation which it, in turn, suppresses. Secondly, the high opacity to LW photons which is built up in the relic H ii regions left by the first stars acts to diminish the global LW background. Accounting for a self-regulated LW background, we estimate a lower limit for the rate of Pop III star formation in minihaloes at z≳ 15. Further, we simulate the formation of a ‘first galaxy’ with virial temperature Tvir≳ 104K and total mass ≳108M⊙ at z≳ 10, and find that complete suppression of previous Pop III star formation is unlikely, with stars of ≳100 M⊙ (Pop III.1) and ≳10 M⊙ (Pop III.2) likely forming. Finally, we discuss the implications of these results for the nature of the first galaxies, which may be observed by future missions such as the James Webb Space Telescope.