Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust

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Ade , P A R , Juvela , M , Keihänen , E , Kurki-Suonio , H , Suur-Uski , A -S , Valiviita , J & Planck Collaboration 2015 , ' Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust ' Astronomy & Astrophysics , vol. 576 , A104 . DOI: 10.1051/0004-6361/201424082

Title: Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
Author: Ade, P. A. R.; Aghanim, N.; Alina, D.; Alves, M. I. R.; Armitage-Caplan, C.; Amaue, M.; Arzoumanian, D.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banda, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Levy, A.; Bernard, J. -P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Burigana, C.; Butler, R. C.; Cardoso, J. -F.; Catalano, A.; Chamballu, A.; Chary, R. -R.; Chiang, H. C.; Christensen, P. R.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, E.; Danese, L.; Davies, R. D.; Davis, R. J.; Juvela, M.; Keihänen, Elina; Keskitalo, R.; Kurki-Suonio, H.; Suur-Uski, A. -S.; Valiviita, J.
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Particle Physics and Astrophysics
University of Helsinki, Helsinki Institute of Physics (HIP) (-2009)
University of Helsinki, Department of Physics
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Helsinki Institute of Physics
Date: 2015-04
Language: eng
Number of pages: 33
Belongs to series: Astronomy & Astrophysics
ISSN: 0004-6361
URI: http://hdl.handle.net/10138/233355
Abstract: This paper presents an overview of the polarized sky as seen by Planck HFI at 353GHz, which is the most sensitive Planck channel for dust polarization. We construct and analyse maps of dust polarization fraction and polarization angle at 1 degrees resolution, taking into account noise bias and possible systematic effects. The sensitivity of the Planck HFI polarization measurements allows for the first time a mapping of Galactic dust polarized emission on large scales, including low column density regions. We find that the maximum observed dust polarization fraction is high (p(max) = 19.8%), in particular in some regions of moderate hydrogen column density (N-H <2 x 10(21) cm(-2)). The polarization fraction displays a large scatter at NH below a few 10(21) cm(-2). There is a general decrease in the dust polarization fraction with increasing column density above N-H similar or equal to 1 x 10(21) cm(-2) and in particular a sharp drop above N-H similar or equal to 1.5 x 10(22) cm(-2). We characterize the spatial structure of the polarization angle using the angle dispersion function. We find that the polarization angle is ordered over extended areas of several square degrees, separated by filamentary structures of high angle dispersion function. These appear as interfaces where the sky projection of the magnetic field changes abruptly without variations in the column density. The polarization fraction is found to be anti-correlated with the dispersion of polarization angles. These results suggest that, at the resolution of 1 degrees, depolarization is due mainly to fluctuations in the magnetic field orientation along the line of sight, rather than to the loss of grain alignment in shielded regions. We also compare the polarization of thermal dust emission with that of synchrotron measured with Planck, low-frequency radio data, and Faraday rotation measurements toward extragalactic sources. These components bear resemblance along the Galactic plane and in some regions such as the Fan and North Polar Spur regions. The poor match observed in other regions shows, however, that dust, cosmic-ray electrons, and thermal electrons generally sample different parts of the line of sight.
Subject: ISM: general
dust, extinction
ISM: magnetic fields
ISM: clouds
submillimeter: ISM
PROBE WMAP OBSERVATIONS
RADIATIVE TORQUE ALIGNMENT
FORMING MOLECULAR CLOUDS
MAGNETIC-FIELD GEOMETRY
GRAIN ALIGNMENT
INTERSTELLAR TURBULENCE
ROTATION MEASURES
SOUTHERN SKY
EXTRAGALACTIC SOURCES
1.4 GHZ
115 Astronomy, Space science
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