Astrophys. J., 893, 13-13 (2020/April-2)
Confirmation of enhanced long-wavelength dust emission in OMC 2/3.
MASON B., DICKER S., SADAVOY S., STANCHFIELD S., MROCZKOWSKI T., ROMERO C., FRIESEN R., SARAZIN C., SIEVERS J., STANKE T. and DEVLIN M.
Abstract (from CDS):
Previous continuum observations from the MUSTANG camera on the Green Bank Telescope (GBT) of the nearby star-forming filament OMC 2/3 found elevated emission at 3.3 mm relative to shorter-wavelength data. As a consequence, the inferred dust emissivity index obtained from modified blackbody dust spectra was considerably lower than what is typically measured on ∼0.1 pc scales in nearby molecular clouds. Here we present new observations of OMC 2/3 collected with the MUSTANG-2 camera on the GBT that confirm this elevated emission. We also present for the first time sensitive 1 cm observations made with the Ka-band receiver on the GBT, which also show higher than expected emission. We use these observations-along with Herschel, JCMT, Mambo, and GISMO data-to assemble spectral energy distributions (SEDs) of a variety of structures in OMC 2/3 spanning the range 160 µm to 1 cm. The data at 2 mm and shorter are generally consistent with a modified blackbody spectrum and a single value of β ∼ 1.6. The 3 mm and 1 cm data, however, lie well above such an SED. The spectrum of the long-wavelength excess is inconsistent with both free-free emission and standard "Spinning Dust" models for Anomalous Microwave Emission (AME). The 3 mm and 1 cm data could be explained by a flatter dust emissivity at wavelengths shorter than 2 mm, potentially in concert with AME in some regions.
© 2020. The American Astronomical Society. All rights reserved.
Dust continuum emission - Interstellar dust - Molecular clouds - Dense interstellar clouds - Interstellar filaments - Star formation - Protostars
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