Universität zu Köln

Juvela, Mika ORCID: 0000-0002-5809-4834, Guillet, Vincent, Liu, Tie, Ristorcelli, Isabelle, Pelkonen, Veli-Matti ORCID: 0000-0002-8898-1047, Alina, Dana ORCID: 0000-0001-5403-356X, Bronfman, Leonardo ORCID: 0000-0002-9574-8454, Eden, David J., Kim, Kee Tae, Koch, Patrick M., Kwon, Woojin, Lee, Chang Won, Malinen, Johanna, Micelotta, Elisabetta ORCID: 0000-0002-6555-5109, Montillaud, Julien, Rawlings, Mark G., Sanhueza, Patricio, Soam, Archana, Traficante, Alessio ORCID: 0000-0003-1665-6402, Ysard, Nathalie and Zhang, Chuan-Peng (2018). Dust spectrum and polarisation at 850 mu m in the massive IRDC G035.39-00.33. Astron. Astrophys., 620. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. The sub-millimetre polarisation of dust emission from star-forming clouds carries information on grain properties and on the effects that magnetic fields have on cloud evolution. Aims. Using observations of a dense filamentary cloud G035.39-00.33, we aim to characterise the dust emission properties and the variations of the polarisation fraction. Methods. JCMT SCUBA-2/POL-2 observations at 850 mu m were combined with Planck 850 mu m (353 GHz) data to map polarisation fraction at small and large scales. With previous total intensity SCUBA-2 observations (450 and 850 mu m) and Herschel data, the column densities were determined via modified black-body fits and via radiative transfer modelling. Models were constructed to examine how the observed polarisation angles and fractions depend on potential magnetic field geometries and grain alignment processes. Results. POL-2 data show clear changes in the magnetic field orientation. These are not in contradiction with the uniform orientation and almost constant polarisation fraction seen by Planck, because of the difference in the beam sizes and the POL-2 data being affected by spatial filtering. The filament has a peak column density of N(H-2) similar to 7 x 10(22) cm(-2), a minimum dust temperature of T similar to 12 K, and a mass of similar to 4300 M-circle dot for the area N(H-2) > 5 x 10(21) cm(-2). The estimated average value of the dust opacity spectral index is beta similar to 1.9. The ratio of sub-millimetre and J-band optical depths is tau (250 mu m)/tau(J) similar to 2.5 x 10(-3), more than four times the typical values for diffuse medium. The polarisation fraction decreases as a function of column density to p similar to 1% in the central filament. Because of noise, the observed decrease of p(N) is significant only at N(H-2) > 2 x 10(22) cm(-2). The observations suggest that the grain alignment is not constant. Although the data can be explained with a complete loss of alignment at densities above similar to 10(4) cm(-3) or using the predictions of radiative torques alignment, the uncertainty of the field geometry and the spatial filtering of the SCUBA-2 data prevent strong conclusions. Conclusions. The G035.39-00.33 filament shows strong signs of dust evolution and the low polarisation fraction is suggestive of a loss of polarised emission from its densest parts.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Juvela, Mika UNSPECIFIED orcid.org/0000-0002-5809-4834 UNSPECIFIED Guillet, Vincent UNSPECIFIED UNSPECIFIED UNSPECIFIED Liu, Tie UNSPECIFIED UNSPECIFIED UNSPECIFIED Ristorcelli, Isabelle UNSPECIFIED UNSPECIFIED UNSPECIFIED Pelkonen, Veli-Matti UNSPECIFIED orcid.org/0000-0002-8898-1047 UNSPECIFIED Alina, Dana UNSPECIFIED orcid.org/0000-0001-5403-356X UNSPECIFIED Bronfman, Leonardo UNSPECIFIED orcid.org/0000-0002-9574-8454 UNSPECIFIED Eden, David J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kim, Kee Tae UNSPECIFIED UNSPECIFIED UNSPECIFIED Koch, Patrick M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kwon, Woojin UNSPECIFIED UNSPECIFIED UNSPECIFIED Lee, Chang Won UNSPECIFIED UNSPECIFIED UNSPECIFIED Malinen, Johanna UNSPECIFIED UNSPECIFIED UNSPECIFIED Micelotta, Elisabetta UNSPECIFIED orcid.org/0000-0002-6555-5109 UNSPECIFIED Montillaud, Julien UNSPECIFIED UNSPECIFIED UNSPECIFIED Rawlings, Mark G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanhueza, Patricio UNSPECIFIED UNSPECIFIED UNSPECIFIED Soam, Archana UNSPECIFIED UNSPECIFIED UNSPECIFIED Traficante, Alessio UNSPECIFIED orcid.org/0000-0003-1665-6402 UNSPECIFIED Ysard, Nathalie UNSPECIFIED UNSPECIFIED UNSPECIFIED Zhang, Chuan-Peng UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-165402
DOI:	10.1051/0004-6361/201833245
Journal or Publication Title:	Astron. Astrophys.
Volume:	620
Date:	2018
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GOULD BELT SURVEY; MAGNETIC-FIELD; GRAIN ALIGNMENT; MOLECULAR CLOUD; DARK CLOUD; RADIATIVE TORQUES; INFRARED OBSERVATIONS; SCUBA-2 OBSERVATIONS; TAURUS; POLARIMETRY Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16540