2004/01/31 by Andrei Mesinger, Zoltan Haiman, Renyue Cen · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/422898
published as Astrophys.J. 613 (2004) 23-35 · modified version, accepted to appear in ApJ, vol. 613, 20 September 2004
arxiv created 2004/06/07 · openalex publication_date 2004/09/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We quantify and discuss the footprints of neutral hydrogen in the intergalactic medium (IGM) on the spectra of high-redshift ( z ~ 6) sources, using mock spectra generated from hydrodynamical simulations of the IGM. We show that it should be possible to extract relevant parameters, including the mean neutral fraction in the IGM and the radius of the local cosmological Strömgren region, from the flux distribution in the observed spectra of distant sources. We focus on quasars, but a similar analysis is applicable to galaxies and gamma-ray burst (GRB) afterglows. We explicitly include uncertainties in the spectral shape of the assumed source template near the Lyα line. Our results suggest that a mean neutral hydrogen fraction, x H , of unity can be statistically distinguished from x H ≈ 10 -2 by combining the spectra of tens of bright ( M ≈ -27) quasars. Alternatively, the same distinction can be achieved using the spectra of several hundred sources that are ~100 times fainter. Furthermore, if the radius of the Strömgren sphere can be independently constrained to within ~10%, this distinction can be achieved using a single source. The information derived from such spectra will help in settling the current debate as to what extent the universe was reionized at redshifts near z ~ 6.