Elizabeth R. Fernandez, Ilian T. Iliev, Eiichiro Komatsu, Paul R. Shapiro
Current observations suggest that the universe was reionized sometime before
z~6. One way to observe this epoch of the universe is through the Near Infrared
Background (NIRB), which contains information about galaxies which may be too
faint to be observed individually. We calculate the angular power spectrum
(C_l) of the NIRB fluctuations caused by the distribution of these galaxies.
Assuming a complete subtraction of any post-reionization component, C_l will be
dominated by galaxies responsible for completing reionization (e.g., z~6). The
shape of C_l at high l is sensitive to the amount of non-linear bias of dark
matter halos hosting galaxies. As the non-linear bias depends on the mass of
these halos, we can use the shape of C_l to infer typical masses of dark matter
halos responsible for completing reionization. We extend our previous study by
using a higher-resolution N-body simulation, which can resolve halos down to
10^8 M_sun. We also include improved radiative transfer, which allows for the
suppression of star formation in small-mass halos due to photo-ionization
heating. As the non-linear bias enhances the dark-matter-halo power spectrum on
small scales, we find that C_l is steeper for the case with a complete
suppression of small sources or partial suppression of star formation in small
halos (the minimum galaxy mass is M_min=10^9 M_sun in ionized regions and
M_min=10^8 M_sun in neutral regions) than the case in which these small halos
were unsuppressed. In all cases, we do not see a turn-over toward high l in the
shape of l^2 C_l.
View original:
http://arxiv.org/abs/1112.2064
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