Year: 2006
Type: review
Abstract: Observations have set the first constraints on the epoch of reionization (EoR), corresponding to the formation epoch of the first luminous objects. Studies of Gunn-Peterson (GP) absorption indicate a rapid increase in the neutral fraction of the intergalactic medium (IGM) from xHI< 10−4at z ≤ 5.5, to xHI> 10−3, perhaps up to 0.1, at z∼6, while the large scale polarization of the cosmic microwave background (CMB) implies a significant ionization fraction extending to higher redshifts, z∼11 ± 3. These results, as well as observations of galaxy populations, suggest that reionization is a process that begins as early as z∼14, and ends with the “percolation” phase at z∼6 to 8. Low luminosity star-forming galaxies are likely the dominant sources of reionizing photons. Future low-frequency radio telescopes will make direct measurements of HI 21-cm emission from the neutral IGM during the EoR, and measurements of secondary CMB temperature anisotropy will provide details of the dynamics of the reionized IGM.
Authors: Xiaohui Fan, C.L. Carilli, B. Keating
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2136969532