Multi-Wavelength SEDs of Herschel Selected Galaxies in the COSMOS Field
  We combine Herschel PACS and SPIRE maps of the full 2 deg^2 COSMOS field with
existing multi-wavelength data to obtain template and model-independent
optical-to-far-infrared spectral energy distributions (SEDs) for 4,218
Herschel-selected sources with log(L_IR/L_sun) = 9.4-13.6 and z = 0.02-3.54.
Median SEDs are created by binning the optical to far-infrared (FIR) bands
available in COSMOS as a function of infrared luminosity. Herschel probes
rest-frame wavelengths where the bulk of the infrared radiation is emitted,
allowing us to more accurately determine fundamental dust properties of our
sample of infrared luminous galaxies. We find that the SED peak wavelength
(lambda_peak) decreases and the dust mass (M_dust) increases with increasing
total infrared luminosity (L_IR). In the lowest infrared luminosity galaxies
(log(L_IR/L_sun) = 10.0-11.5), we see evidence of Polycyclic Aromatic
Hydrocarbons (PAH) features (lambda=7-9 um), while in the highest infrared
luminosity galaxies (L_IR > 10^12 L_sun) we see an increasing contribution of
hot dust and/or power-law emission, consistent with the presence of heating
from an active galactic nucleus (AGN). We study the relationship between
stellar mass and star formation rate of our sample of infrared luminous
galaxies and find no evidence that Herschel-selected galaxies follow the
SFR/M_* "main sequence" as previously determined from studies of optically
selected, star-forming galaxies. Finally, we compare the mid-infrared (MIR) to
FIR properties of our infrared luminous galaxies using the previously defined
diagnostic, IR8 = L_IR / L_8, and find that galaxies with L_IR > 10^11.3 L_sun
tend to systematically lie above (~3-5) the IR8 "infrared main sequence",
suggesting either suppressed PAH emission or an increasing contribution from
AGN heating.
