CONNECTING REIONIZATION TO THE LOCAL UNIVERSE
We present results of combined N-body and three-dimensional reionization calculations to determine the relationship between reionization history and local environment in a volume of 1 Gpc h {sup -1} across and a resolution of about 1 Mpc. We achieve this by applying three-dimensional simulations of reionization, based on the extended Press-Schechter formalism, to the same initial conditions as the N-body simulations. We resolve about 2 x 10{sup 6} halos of mass greater than {approx}10{sup 12} M {sub sun} at z = 0, and determine the relationship between halo mass and reionization epoch for galaxies and clusters. For our fiducial reionization model, in which reionization begins at z {approx} 15 and ends by z {approx} 6, we find a strong bias for cluster-size halos to be in the regions that reionized first, at redshifts 10 < z < 15. Consequently, material in clusters was reionized within relatively small regions, on the order of a few Mpc, implying that all clusters in our calculation were reionized by their own progenitors. Milky Way mass halos were on average reionized later and by larger regions, with a distribution most similar to the global one, indicating that low-mass halos are nearly uncorrelated with reionization when only halo mass is taken as a prior. On average, most halos with mass less than 10{sup 13} M {sub sun} were reionized internally, while almost all halos with masses greater than 10{sup 14} M {sub sun} were reionized by their own progenitors. We briefly discuss the implications of this work in light of the 'missing satellites' problem and how this new approach may be extended further.
- OSTI ID:
- 21371853
- Journal Information:
- Astrophysical Journal (Online), Vol. 703, Issue 2; Other Information: DOI: 10.1088/0004-637X/703/2/L167; ISSN 1538-4357
- Country of Publication:
- United States
- Language:
- English
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