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Balloon-Borne Submillimeter Polarimetry of the Vela C Molecular Cloud: Systematic Dependence of Polarization Fraction on Column Density and Local Polarization-Angle Dispersion

Fissel, Laura M. and Moncelsi, Lorenzo (2016) Balloon-Borne Submillimeter Polarimetry of the Vela C Molecular Cloud: Systematic Dependence of Polarization Fraction on Column Density and Local Polarization-Angle Dispersion. Astrophysical Journal, 824 (2). Art. No. 134. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20160916-130319656

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Abstract

We present results for Vela C obtained during the 2012 flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry. We mapped polarized intensity across almost the entire extent of this giant molecular cloud, in bands centered at 250, 350, and 500 μm. In this initial paper, we show our 500 μm data smoothed to a resolution of 2farcm5 (approximately 0.5 pc). We show that the mean level of the fractional polarization p and most of its spatial variations can be accounted for using an empirical three-parameter power-law fit, p ∝ N^(-0.45) S^(-0.60), where N is the hydrogen column density and S is the polarization-angle dispersion on 0.5 pc scales. The decrease of p with increasing S is expected because changes in the magnetic field direction within the cloud volume sampled by each measurement will lead to cancellation of polarization signals. The decrease of p with increasing N might be caused by the same effect, if magnetic field disorder increases for high column density sightlines. Alternatively, the intrinsic polarization efficiency of the dust grain population might be lower for material along higher density sightlines. We find no significant correlation between N and S. Comparison of observed submillimeter polarization maps with synthetic polarization maps derived from numerical simulations provides a promising method for testing star formation theories. Realistic simulations should allow for the possibility of variable intrinsic polarization efficiency. The measured levels of correlation among p, N, and S provide points of comparison between observations and simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.3847/0004-637X/824/2/134DOIArticle
http://iopscience.iop.org/article/10.3847/0004-637X/824/2/134/metaPublisherArticle
http://arxiv.org/abs/1509.05298arXivArticle
ORCID:
AuthorORCID
Fissel, Laura M.0000-0002-3242-8154
Moncelsi, Lorenzo0000-0002-4242-3015
Additional Information:© 2016 The American Astronomical Society. Received 2015 September 6; revised 2016 February 21; accepted 2016 April 26; published 2016 June 21. The authors like to thank the referee for a detailed and thoughtful review that has helped to strengthen the paper. The BLASTPol collaboration acknowledges support from NASA (through grant numbers NAG5-12785, NAG5-13301, NNGO-6GI11G, NNX0-9AB98G, and the Illinois Space Grant Consortium), the Canadian Space Agency (CSA), the Leverhulme Trust through the Research Project Grant F/00 407/BN, the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation, the Ontario Innovation Trust, the Dunlap Institute for Astronomy and Astrophysics, and the US National Science Foundation Office of Polar Programs. LMF was supported in part by an NSERC Postdoctoral Fellowship. BD is supported through a NASA Earth and Space Science Fellowship. CBN also acknowledges support from the Canadian Institute for Advanced Research. FPS is supported by the CAPES grant 2397/13-7. Z-YL is supported in part by NSF AST1313083 and NASA NNX14AB38G. FP thanks the Spanish Ministry of Economy and Competitiveness (MINECO) under the Consolider-Ingenio project CSD2010-00064. The authors would also like to thank Diego Falceta-Gonçalves for making available line integral convolution code, which was used in making the drapery image shown in Figure 5. Finally, we thank the Columbia Scientific Balloon Facility (CSBF) staff for their outstanding work.
Funders:
Funding AgencyGrant Number
NASANAG5-12785
NASANAG5-13301
NASANNGO-6GI11G
NASANNX0-9AB98G
Illinois Space Grant Consortium UNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
Leverhulme TrustF/00 407/BN
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Ontario Innovation TrustUNSPECIFIED
Dunlap Institute for Astronomy and AstrophysicsUNSPECIFIED
NSFUNSPECIFIED
NASAUNSPECIFIED
Canadian Institute for Advanced ResearchUNSPECIFIED
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)2397/13-7
NSFAST1313083
NASANNX14AB38G
Ministerio de Economía y Competitividad (MINECO)CSD2010-00064
Subject Keywords:dust, extinction; instrumentation: polarimeters; ISM: individual objects (Vela C) ; ISM: magnetic fields; stars: formation; techniques: polarimetric
Record Number:CaltechAUTHORS:20160916-130319656
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160916-130319656
Official Citation:Laura M. Fissel et al 2016 ApJ 824 134
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70403
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 Sep 2016 21:30
Last Modified:08 Jul 2019 18:48

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