A physical model for the origin of the diffuse cosmic infrared
  background
  We present a physical model for origin of the cosmic diffuse infrared
background (CDIRB). By utilizing the observed stellar mass function and its
evolution as input to a semi-empirical model of galaxy formation, we isolate
the physics driving diffuse IR emission. The model includes contributions from
three primary sources of IR emission: steady-state star formation owing to
isolated disk galaxies, interaction-driven bursts of star formation owing to
close encounters and mergers, and obscured active galactic nuclei (AGN). We
find that most of the CDIRB is produced by equal contributions from objects at
z=0.5-1 and z>1, as suggested by recent observations. Of those sources, the
vast majority of the emission originates in systems with low to moderate IR
luminosities (L_{IR}<10^{12} $L_sun); the most luminous objects contribute
significant flux only at high-redshifts (z>2). All star formation in ongoing
mergers accounts for <10% of the total at all wavelengths and redshifts, while
emission directly attributable to the interaction-driven burst itself accounts
for <5%. We furthermore find that obscured AGN contribute <1-2% of the CDIRB at
all wavelengths and redshifts, with a strong upper limit of less than 4% of the
total emission. Finally, since electron-positron pair production interactions
with the CDIRB represent the primary source of opacity to very high energy
(VHE: E_\gamma > 1 TeV) \gamma-rays, the model provides predictions for the
optical depth of the Universe to the most energetic photons. We find that these
predictions agree with observations of high-energy cutoffs at TeV energies in
nearby blazars, and suggest that while the Universe is extremely optically
thick at >10 TeV, the next generation of VHE \gamma-ray telescopes can
reasonably expect detections from out to 50-150 Mpc.
