Kari Helgason, Massimo Ricotti, Alexander Kashlinsky
We model fluctuations in the Cosmic Infrared Background (CIB) arising from
known galaxy populations using 230 measured UV, optical and NIR luminosity
functions (LF) from a variety of surveys spanning a wide range of redshifts. We
compare best-fit Schechter parameters across the literature and find clear
indication of evolution with redshift. Providing fitting formulae for the
multi-band evolution of the LFs, we calculate the total emission redshifted
into the near-IR bands in the observer frame and recover the galaxy number
counts in the 0.45-4.5 micron range. Our empirical approach, in conjunction
with a halo model describing the clustering of galaxies, allows us to compute
the fluctuations of the unresolved CIB and compare the models to current
measurements. We find that fluctuations from known galaxy populations are
unable to account for more than 20% of the CIB clustering signal seen by
Spitzer/IRAC and AKARI/IRC at angular scales out to at least 5 arcmin. This
holds true even if the LFs are extrapolated with the steepest faint-end slope
allowed by data out to faint magnitudes. A rapid increase in the number of
low-redshift dwarf galaxies just beyond the detection thresholds of current
surveys would violate the shot noise levels seen in the data. We also show that
removing resolved sources to progressively fainter magnitude limits, isolates
CIB fluctuations arising from higher redshifts. Our empirical approach suggests
that known galaxy populations are not responsible for the bulk of the
fluctuation signal seen in the measurements.
View original:
http://arxiv.org/abs/1201.4398
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