The 21-cm Background from the Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization
Abstract
The H atoms inside minihalos (i.e. halos with virial temperatures T_vir < 10^4 K, in the mass range roughly from 10^4 M_sun to 10^8 M_sun) during the cosmic dark ages in a LCDM universe produce a redshifted background of collisionally-pumped 21-cm line radiation which can be seen in emission relative to the cosmic microwave background (CMB). Previously, we used semi-analytical calculations of the 21-cm signal from individual halos of different mass and redshift and the evolving mass function of minihalos to predict the mean brightness temperature of this 21-cm background and its angular fluctuations. Here we use high-resolution cosmological N-body and hydrodynamic simulations of structure formation at high redshift (z > 8) to compute the mean brightness temperature of this background from both minihalos and the intergalactic medium (IGM) prior to the onset of Ly-alpha radiative pumping. We find that the 21-cm signal from gas in collapsed, virialized minihalos dominates over that from the diffuse shocked gas in the IGM.
Keywords
Cite
@article{arxiv.astro-ph/0509651,
title = {The 21-cm Background from the Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization},
author = {Kyungjin Ahn and Paul R. Shapiro and Marcelo A. Alvarez and Ilian T. Iliev and Hugo Martel and Dongsu Ryu},
journal= {arXiv preprint arXiv:astro-ph/0509651},
year = {2009}
}
Comments
8 pages, 5 figures. To appear in proceedings of UC Irvine May 2005 workshop on "First Light & Reionization", eds. E. Barton & A. Cooray, New Astronomy Reviews, in press