Cosmic reionization redux

Nickolay Y. Gnedin, Xiaohui Fan

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

We show that numerical simulations of reionization that resolve the Lyman limit systems (and, thus, correctly count absorptions of ionizing photons) have converged to about a 10% level for 5 < z < 6.2 and are in reasonable agreement (within 10%) with the SDSS data in this redshift interval. The SDSS data thus constrain the redshift of overlap of cosmic H II regions to z OVL = 6.1 ± 0.15. At higher redshifts, the simulations are far from convergence on the mean Gunn-Peterson optical depth but achieve good convergence for the mean neutral hydrogen fraction. The simulations that fit the SDSS data, however, do not have nearly enough resolution to resolve the earliest episodes of star formation and are very far from converging on the precise value of the optical depth to Thomson scattering - any value between 6% and 10% is possible, depending on the convergence rate of the simulations and the fractional contribution of Population III stars. This is generally consistent with the third-year WMAP results, but much higher resolution simulations are required to come up with the sufficiently precise value for the Thomson optical depth that can be statistically compared with the WMAP data.

Original languageEnglish (US)
Pages (from-to)1-6
Number of pages6
JournalAstrophysical Journal
Volume648
Issue number1 I
DOIs
StatePublished - Sep 1 2006

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optical thickness
optical depth
simulation
Population III stars
Thomson scattering
H II regions
star formation
scattering
hydrogen
intervals
high resolution
photons
rate

Keywords

  • Cosmology: theory
  • Galaxies: formation
  • Intergalactic medium
  • Large-scale structure of universe

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Cosmic reionization redux. / Gnedin, Nickolay Y.; Fan, Xiaohui.

In: Astrophysical Journal, Vol. 648, No. 1 I, 01.09.2006, p. 1-6.

Research output: Contribution to journalArticle

Gnedin, Nickolay Y. ; Fan, Xiaohui. / Cosmic reionization redux. In: Astrophysical Journal. 2006 ; Vol. 648, No. 1 I. pp. 1-6.
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