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An Imprint of the Galactic Magnetic Field in the Diffuse Unpolarized Dust Emission

Hensley, Brandon S. and Zhang, Cheng and Bock, James J. (2019) An Imprint of the Galactic Magnetic Field in the Diffuse Unpolarized Dust Emission. Astrophysical Journal, 887 (2). Art. No. 159. ISSN 1538-4357. doi:10.3847/1538-4357/ab5183.

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It is well known that aligned, aspherical dust grains emit polarized radiation and that the degree of polarization depends on the angle ψ between the interstellar magnetic field and the line of sight (LOS). However, anisotropy of the dust absorption cross sections also modulates the total intensity of the radiation as the viewing geometry changes. We report a detection of this effect in the high Galactic latitude Planck data, finding that the 353 GHz dust intensity per N_(H I) is smaller when the Galactic magnetic field is mostly in the plane of the sky and larger when the field is mostly along the LOS. These variations are of opposite sign and roughly equal magnitude as the changes in polarized intensity per N_(H I) with ψ, as predicted. In principle, the variation in intensity can be used in conjunction with the dust polarization angle to constrain the full 3D orientation of the Galactic magnetic field.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hensley, Brandon S.0000-0001-7449-4638
Zhang, Cheng0000-0001-8288-5823
Bock, James J.0000-0002-5710-5212
Additional Information:© 2019 The American Astronomical Society. Received 2019 September 14; revised 2019 October 23; accepted 2019 October 24; published 2019 December 17. It is a pleasure to thank François Boulanger, Susan Clark, Bruce Draine, Laura Fissel, and Vincent Guillet for stimulating discussions and helpful suggestions. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Facilities: Effelsberg - Effelsberg Radio Telescope, Parkes - Parkes Radio Telescope, Planck - European Space Agency's Planck space observatory. Software: Astropy (Astropy Collaboration et al. 2013, 2018), corner (Foreman-Mackey 2016), emcee (Foreman-Mackey et al. 2013), HEALPix (Górski et al. 2005), healpy (Zonca et al. 2019), Matplotlib (Hunter 2007), NumPy (van der Walt et al. 2011).
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:Interstellar dust; Interstellar magnetic fields; Dust continuum emission; H I line emission
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Interstellar dust (836); Interstellar magnetic fields (845); Dust continuum emission (412); H I line emission (690)
Record Number:CaltechAUTHORS:20190925-100235448
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Official Citation:Brandon S. Hensley et al 2019 ApJ 887 159
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98848
Deposited By: Tony Diaz
Deposited On:25 Sep 2019 17:10
Last Modified:16 Nov 2021 17:42

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