2008/06/30 by C. -A. Faucher-Giguere, Claude‐André Faucher‐Giguère, Adam Lidz +5 · 87 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #COSMIC cancer database #Emissivity #Galaxies: Formation, Evolution, Phenomena #Galaxy #Ionization #Luminosity #Luminosity function #Photoionization #Physics #Quasar #Redshift #Reionization #Star formation #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/590409
published in The Astrophysical Journal 682(1), L9-L12 (IOP Publishing) · 5 pages, including 1 figure, published by ApJ
openalex publication_date 2008/07/08 · arxiv created 2008/07/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the implications of our measurement of the Lyα forest opacity at redshifts 2 ⩽ z ⩽ 4.2 from a sample of 86 high-resolution quasar spectra for the evolution of the cosmic ultraviolet luminosity density and its sources. The derived hydrogen photoionization rate Γ is remarkably flat over this redshift range, implying an increasing comoving ionizing emissivity with redshift. Because the quasar luminosity function is strongly peaked near z ∼ 2, star-forming galaxies likely dominate the ionizing emissivity at z ≳ 3. Our measurement argues against a star formation rate density declining beyond z ∼ 3, in contrast to existing state-of-the-art determinations of the cosmic star formation history from direct galaxy counts. Stellar emission from galaxies therefore likely reionized the universe.