  Recent observations from the MUSTANG2 instrument on the Green Bank Telescope
have revealed evidence of enhanced long-wavelength emission in the dust
spectral energy distribution (SED) in the Orion Molecular Cloud (OMC) 2/3
filament on 25" (0.1 pc) scales. Here we present a measurement of the SED on
larger spatial scales (map size 0.5-3 degrees or 3-20 pc), at somewhat lower
resolution (120", corresponding to 0.25 pc at 400 pc) using data from the
Herschel satellite and Atacama Cosmology Telescope (ACT). We then extend the
120"-scale investigation to other regions covered in the Herschel Gould Belt
Survey (HGBS) specifically: the dense filaments in the southerly regions of
Orion A; Orion B; and Serpens-S. Our dataset in aggregate covers approximately
10 square degrees, with continuum photometry spanning from 160um to 3mm. These
OMC 2/3 data display excess emission at 3mm, though less (10.9% excess) than
what is seen at higher resolution. Strikingly, we find that the enhancement is
present even more strongly in the other filaments we targeted, with an average
excess of 42.4% and 30/46 slices showing an inconsistency with the modified
blackbody to at least 4{\sigma}. Applying this analysis to the other targeted
regions, we lay the groundwork for future high-resolution analyses.
Additionally, we also consider a two-component dust model motivated by Planck
results and an amorphous grain dust model. While both of these have been
proposed to explain deviations in emission from a generic modified blackbody
(MBB), we find that they have significant drawbacks, requiring many spectral
points or lacking experimental data coverage.
