Abstract
We combine the high-resolution Aquarius simulations with three-dimensional
models of reionization based on the initial density field of the Aquarius
parent simulation, Millennium-II, to study the impact of patchy reionization on
the faint satellite population of Milky Way halos. Because the Aquarius suite
consists of zoom-in simulations of halos in the Millennium-II volume, we follow
the formation of substructure and the growth of reionization bubbles due to the
larger environment simultaneously, and thereby determine the reionization
redshifts of satellite candidates. We do this for four different reionization
models, and also compare results to instantaneous reionization. Using a simple
procedure for selecting satellites and assigning luminosities in the
simulations, we compare the resulting satellite populations. We find that the
overall number of satellites depends sensitively on the reionization model,
with a factor of 3-4 difference between the four models for a given host halo,
though the difference is entirely in the population of faint satellites (M_V >
-10). In addition, we find that for a given reionization model the total number
of satellites differ by 10-20% between the patchy and homogeneous scenarios.
However, the halo-halo scatter from the six Aquarius halos is large, up to a
factor of 2-3, and so comparable to the difference between reionization
scenarios. In order to use the population of faint dwarf galaxies around the
Milky Way as a probe of the local reionization history, then, it is necessary
to first better understand the general distribution of substructure around
Milky Way-mass halos. (Abridged.)
Description
[1105.2293] The Effects of Patchy Reionization on Satellite Galaxies of the Milky Way
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