The 21 centimeter background from the cosmic dark ages: minihalos and the intergalactic medium before reionization
Dec, 2005
10 pages
Published in:
- Astrophys.J. 646 (2006) 681
Contribution to:
e-Print:
- astro-ph/0512516 [astro-ph]
DOI:
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Abstract: (arXiv)
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 LambdaCDM 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.- Cosmology
- Theory
- Diffuse radiation
- Intergalactic medium
- Large-scale structure of universe
- Radio lines
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