The Cosmic Near Infrared Background II: Fluctuations
  The Near Infrared Background (NIRB) is one of a few methods that can be used
to observe the redshifted light from early stars at a redshift of six and
above. Fluctuations of the NIRB can provide information on the first
structures, such as halos and their surrounding ionized regions in the IGM. We
combine, for the first time, N-body simulations, radiative transfer code, and
analytic calculations of luminosity of early structures to predict the angular
power spectrum (C_l) of fluctuations in the NIRB. We study the effects of
various assumptions about the stellar mass, the initial mass spectrum of stars,
metallicity, the star formation efficiency (f_*), the escape fraction of
ionizing photons (f_esc), and the star formation timescale (t_SF), on the
amplitude as well as the shape of C_l. The power spectrum of NIRB fluctuations
is maximized when f_* is the largest (as C_l ~ (f_*)^2) and f_esc is the
smallest. A significant uncertainty in the predicted amplitude of C_l exists
due to our lack of knowledge of t_SF of these galaxies, which is equivalent to
our lack of knowledge of the mass-to-light ratio. We do not see a turnover in
the NIRB angular power spectrum of the halo contribution and explain this as
the effect of high levels of non-linear bias. This is partly due to our choice
of the minimum mass of halos contributing to NIRB, and a smaller minimum mass,
which has a smaller non-linear bias, may still exhibit a turn over. Therefore,
both the amplitude and shape of the NIRB power spectrum provide important
information regarding the nature of sources contributing to the cosmic
reionization. The angular power spectrum of the IGM, in most cases, is much
smaller than the halo angular power spectrum. In addition, low levels of the
observed mean background intensity tend to rule out high values of f_* > 0.2.
