  Cosmic infrared background (CIB) contains emission from epochs inaccessible
to current telescopic studies, such as the era of the first stars. We discuss
theoretical expectations for the CIB contributions from the early population of
massive stars. We then present the latest results from the ongoing project by
our team (Kashlinsky, Arendt, Mather & Moseley 2005,2007a,b,c,) to measure CIB
fluctuations from early epochs using deep Spitzer data. The results show the
existence of significant CIB fluctuations at the IRAC wavelengths (3.6 to 8
mic) which remain after removing galaxies down to very faint levels. These
fluctuations must arise from populations that have a significant clustering
component, but only low levels of the shot noise. Furthermore, there are no
correlations between the source-subtracted IRAC maps and the corresponding
fields observed with the HST ACS at optical wavelengths. Taken together, these
data imply that 1) the sources producing the CIB fluctuations are individually
faint with flux < a few nJy at 3.6 and 4.5 mic; 2) are located within the first
0.7 Gyr (unless these fluctuations can somehow be produced by - so far
unobserved - local galaxies of extremely low luminosity and with the unusual
for local populations clustering pattern), 3) they produce contribution to the
net CIB flux of at least 1-2 nW/m^2/sr at 3.6 and 4.5 mic and must have
mass-to-light ratio significantly below the present-day populations, and 4)
they have angular density of ~ a few per arcsec^2 and are in the confusion of
the present day instruments, but can be individually observable with JWST.
