2000/06/30 by Renyue Cen, Zoltan Haiman · 7 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Electrical and Electromagnetic Research #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Intergalactic travel #Ionization #Line (geometry) #Lyman limit #Optical depth #Quasar #Redshift #Reionization #Spectral line #astro-ph
paper · pdf · doi:10.1086/312937
revised, accepted to ApJ Letters
arxiv created 2000/08/17 · openalex publication_date 2000/10/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
Ionizing sources embedded in the neutral intergalactic medium (IGM) before cosmological reionization generate discrete H II regions. We show that a sufficiently bright quasar (for example, 1/10 as luminous as that recently discovered by Fan et al.) can ionize a large volume, allowing the transmission of a substantial fraction of the flux of its intrinsic Lyα emission line on both sides of the Lyα wavelength. The observed line profile is richly informative. We show that a sufficiently accurate, high spectral resolution ( R ≈ 10 4 ) measurement of the line profile of a bright quasar is feasible using the Next Generation Space Telescope as well as large ground-based telescopes. Such a measurement has two potentially important applications. First, the red side of the Lyα emission line provides a way to measure the quasar lifetime. Second, the blue side provides a direct measure of the density fluctuations of the IGM at the quasar redshift. The estimate of the absorption of the red side is limited by the accuracy to which the intrinsic profile of the Lyα emission line is known. The blue side, however, does not sensitively depend on the intrinsic profile because the former is much narrower than the latter.