Ashton, PC;
Ade, PAR;
Angil, FE;
Benton, SJ;
Devlin, MJ;
Dober, B;
Fissel, LM;
... Ward-Thompson, D; + view all
(2018)
First Observation of the Submillimeter Polarization Spectrum in a Translucent Molecular Cloud.
The Astrophysical Journal
, 857
(1)
, Article 10. 10.3847/1538-4357/aab3ca.
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Abstract
Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM, but a troublesome contaminant for studies of cosmic microwave background polarization. In each case, an understanding of the significance of the polarization signal requires well-calibrated physical models of dust grains. Despite decades of progress in theory and observation, polarized dust models remain largely underconstrained. During its 2012 flight, the balloon-borne telescope BLASTPol obtained simultaneous broadband polarimetric maps of a translucent molecular cloud at 250, 350, and 500 μm. Combining these data with polarimetry from the Planck 850 μm band, we have produced a submillimeter polarization spectrum, the first for a cloud of this type. We find the polarization degree to be largely constant across the four bands. This result introduces a new observable with the potential to place strong empirical constraints on ISM dust polarization models in a previously inaccessible density regime. Compared to models by Draine & Fraisse, our result disfavors two of their models for which all polarization arises due only to aligned silicate grains. By creating simple models for polarized emission in a translucent cloud, we verify that extinction within the cloud should have only a small effect on the polarization spectrum shape, compared to the diffuse ISM. Thus, we expect the measured polarization spectrum to be a valid check on diffuse ISM dust models. The general flatness of the observed polarization spectrum suggests a challenge to models where temperature and alignment degree are strongly correlated across major dust components.
| Type: | Article |
|---|---|
| Title: | First Observation of the Submillimeter Polarization Spectrum in a Translucent Molecular Cloud |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/aab3ca |
| Publisher version: | http://dx.doi.org/10.3847/1538-4357/aab3ca |
| Language: | English |
| Additional information: | © 2018. The American Astronomical Society. All rights reserved. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Dust, extinction – instrumentation: polarimeters – ISM: clouds – polarization – submillimeter: ISM – techniques: polarimetric |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10048743 |
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