2006/04/30 by Leonid Chuzhoy, Paul R. Shapiro · 2 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/510146
published as Astrophys.J.655:843-846,2007 · 4 pages, 4 figures, ApJ, in press
openalex publication_date 2007/01/23 · arxiv created 2007/01/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
During the epoch of reionization a large number of photons were produced with frequencies below the hydrogen Lyman limit. After redshifting into the closest resonance, these photons underwent multiple scatterings with atoms. We examine the effect of these scatterings on the temperature of the neutral intergalactic medium (IGM). Continuum photons, emitted between the Lyα and Lyγ frequencies, heat the gas after being redshifted into the H Lyα or D Lyβ resonance. By contrast, photons emitted between the Lyγ and Lyman limit frequencies produce effective cooling of the gas. Prior to reionization, the equilibrium temperature of ~100 K for hydrogen and helium atoms is set by these two competing processes. At the same time, Lyβ resonance photons thermally decouple deuterium from other species, raising its temperature as high as 10 4 K. Our results have important consequences for the cosmic 21 cm background and the entropy floor of the early IGM, which can affect star formation and reionization.