2001/09/30 by Aparna Venkatesan
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #COSMIC cancer database #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Galaxy #Optical depth #Physics #Redshift #Reionization #astro-ph
paper · pdf · doi:10.1086/340297
published as Astrophys.J. 572 (2002) 15 · Accepted on 15 Feb. 2002 for publication in ApJ, 22 pages with 4 figures; paper's text expanded significantly, new Discussion section, results (table and figures) unchanged from version 1
arxiv created 2002/02/21 · openalex publication_date 2002/06/10 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
Spectroscopic studies of high-redshift objects and increasingly precise data on the cosmic microwave background (CMB) are beginning to independently place strong complementary bounds on the epoch of hydrogen reionization. Parameter estimation from current CMB data continues, however, to be subject to several degeneracies. Here, we focus on those degeneracies in CMB parameter forecasts related to the optical depth to reionization. We extend earlier work on the mutual constraints that such analyses of CMB data and a reionization model may place on each other to a more general parameter set and to the case of data anticipated from the MAP satellite. We focus in particular on a semianalytic model of reionization by the first stars, although the methods here are easily extended to other reionization scenarios. A reionization model can provide useful complementary information for cosmological parameter extraction from the CMB, particularly for the degeneracies between the optical depth and either of the amplitude and index of the primordial scalar power spectrum, which are still present in the most recent data. Alternatively, by using a reionization model, known limits on astrophysical quantities can reduce the forecasted errors on cosmological parameters. Forthcoming CMB data also have the potential to constrain the sites of early star formation, as well as the fraction of baryons that participate in it, if reionization were caused by stellar activity at high redshifts. Finally, we examine the implications of an independent, e.g., spectroscopic, determination of the epoch of reionization for the determination of cosmological parameters from the CMB. This has the potential to significantly strengthen limits from the CMB on parameters such as the index of the power spectrum, while having the considerable advantage of being free of the choice of the reionization model.