Cross-Correlation of Near and Far-Infrared Background Anisotropies as
  Traced by Spitzer and Herschel
  We present the cross-correlation between the far-infrared background
fluctuations as measured with the Herschel Space Observatory at 250, 350, and
500 {\mu}m and the near-infrared background fluctuations with Spitzer Space
Telescope at 3.6 {\mu}m. The cross-correlation between far and near-IR
background anisotropies are detected such that the correlation coefficient at a
few to ten arcminute angular scales decreases from 0.3 to 0.1 when the far-IR
wavelength increases from 250 {\mu}m to 500 {\mu}m. We model the
cross-correlation using a halo model with three components: (a) far-IR bright
or dusty star-forming galaxies below the masking depth in Herschel maps, (b)
near-IR faint galaxies below the masking depth at 3.6 {\mu}m, and (c)
intra-halo light, or diffuse stars in dark matter halos, that likely dominates
fluctuations at 3.6 {\mu}m. The model is able to reasonably reproduce the auto
correlations at each of the far-IR wavelengths and at 3.6 {\mu}m and their
corresponding cross-correlations. While the far and near-IR auto-correlations
are dominated by faint dusty, star-forming galaxies and intra-halo light,
respectively, we find that roughly half of the cross-correlation between near
and far-IR backgrounds is due to the same galaxies that remain unmasked at 3.6
{\mu}m. The remaining signal in the cross-correlation is due to intra-halo
light present in the same dark matter halos as those hosting the same faint and
unmasked galaxies. In this model, the decrease in the cross-correlation signal
from 250 {\mu}m to 500 {\mu}m comes from the fact that the galaxies that are
primarily contributing to 500 {\mu}m fluctuations peak at a higher redshift
than those at 250 {\mu}m.
