COMAP Galactic Science I: Observations of Spinning Dust Emission at 30GHz in Dark Clouds Surrounding the {\lambda}-Orionis Hii Region
Anomalous Microwave Emission (AME) is a major component of Galactic emission in the frequency band 10 to 60 GHz and is commonly modelled as rapidly rotating spinning dust grains. The photodissociation region (PDR) at the boundary of the $\lambda$-Orionis Hii region has been identified by several rec...
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Main Authors | , , , , , , , , , , , , , , , , , |
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Format | Journal Article |
Language | English |
Published |
07.05.2024
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Subjects | |
Online Access | Get full text |
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Summary: | Anomalous Microwave Emission (AME) is a major component of Galactic emission
in the frequency band 10 to 60 GHz and is commonly modelled as rapidly rotating
spinning dust grains. The photodissociation region (PDR) at the boundary of the
$\lambda$-Orionis Hii region has been identified by several recent analyses as
one of the brightest spinning dust emitting sources in the sky. We investigate
the Barnard 30 dark cloud, a dark cloud embedded within the $\lambda$-Orionis
PDR. We use total-power observations of Barnard 30 from the CO Mapping Array
Project (COMAP) pathfinder instrument at 26 to 34GHz with a resolution of 4.5
arcminutes alongside existing data from Planck, WISE, IRAS, ACT, and the
1.447GHz GALFACTS survey. We use aperture photometry and template fitting to
measure the spectral energy distribution of Barnard 30. We find that the
spinning dust is the dominant emission component in the 26 to 34GHz range at
the $7 \sigma$ level ($S_{30GHz} = 2.85\pm0.43$Jy). We find no evidence that
polycyclic aromatic hydrocarbons are the preferred carrier for the spinning
dust emission, suggesting that the spinning dust carriers are due to a mixed
population of very small grains. Finally, we find evidence for variations in
spinning dust emissivity and peak frequency within Barnard 30, and that these
variations are possibly driven by changes in dust grain population and the
total radiation field. Confirming the origin of the variations in the spinning
dust spectrum will require both future COMAP observations at 15GHz combined
with spectroscopic mid-infrared data of Barnard 30. |
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DOI: | 10.48550/arxiv.2405.04383 |