The Optical Depth to Reionization as a Probe of Cosmological and Astrophysical Parameters

Abstract

Current data of high-redshift absorption-line systems imply that hydrogen reionization occurred before redshifts of about 5. Previous works on reionization by the first stars or quasars have shown that such scenarios are described by a large number of cosmological and astrophysical parameters. Here, we adopt a semi-analytic model of stellar reionization in order to quantify how the optical depth to reionization depends on such parameters, and combine this with constraints from the cosmic microwave background (CMB). We find this approach to be particularly useful in alleviating the well-known degeneracy in CMB parameter extraction between the optical depth to reionization and the amplitude of the primordial power spectrum, due to the complementary information from the reionization model. We also examine translating independent limits on astrophysical parameters into those on cosmological parameters, or conversely, how improved determinations of cosmological parameters will constrain astrophysical unknowns.

25 pages with 13 embedded postscript figures; this matches the version accepted for publication in Ap.J., July 1, 2000 issue (vol. 537). Revisions are minor: a few text clarifications or corrections, and figures are now easier to read

References in corpus (2)

• Cosmological Reionization by Stellar Sources
• Zero-Metallicity Stars and the Effects of the First Stars on Reionization

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• The Reionization History at High Redshifts I: Physical Models and New Constraints from CMB Polarization
• Probing the Reionization History of the Universe using the Cosmic Microwave Background Polarization
• Towards a refined cosmic concordance model: joint 11-parameter constraints from CMB and large-scale structure
• Current cosmological constraints from a 10 parameter CMB analysis
• Evolving Spectra of Pop III Stars: Consequences for Cosmological Reionization
• Observing Dark Stars with JWST
• Approximate Analytic Spectra of Reionized CMB Anisotropies and Polarization generated by Relic Gravitational Waves
• Gravitational wave background from Population III black hole formation
• Stochastic background of gravitational waves generated by pre-galactic black holes
• Mutual Constraints Between Reionization Models and Parameter Extraction From Cosmic Microwave Background Data
• Background of gravitational waves from pre-galactic black hole formation