2004/06/30 by Ping He, Jiren Liu, Long‐Long Feng +5 · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/423663
published as Astrophys.J. 614 (2004) 6-16 · 19 pages, 12 figures
openalex publication_date 2004/10/08 · arxiv created 2004/10/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We investigate the 21 cm emission from the epoch between reionization z r and the Gunn-Peterson transparency z GP . According to the lognormal model of the thermal history around reionization, hydrogen clouds in z r > z > z GP are hot and a predominant part of baryonic gas is ionized, but still opaque to Lyα photons. Therefore, 21 cm emission is a distinctive characteristic of this epoch. We show that the 21 cm emission comes from both uncollapsed and collapsing hydrogen clouds. The spatial distribution of the brightness temperature excess δ T b is highly non-Gaussian. It consists of spikes with high δ T b and a low δ T b area between the spikes. The field has the following statistical features: (1) the one-point distributions of δ T b are described approximately by power-law tailed probability distribution functions; (2) the n th-order moment of δ T b is increasing much faster with n than that of a Gaussian field, but slower than that of a lognormal field; (3) the scale-scale correlation of the δ T b field is significant for all scales larger than the Jeans length of the gas. These features would be useful for distinguishing the 21 cm emission of the early clustering from the noise of foreground contamination.