Planck intermediate results XXV : The Andromeda galaxy as seen by Planck

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Ade , P A R , Juvela , M , Keihänen , E , Kurki-Suonio , H , Lähteenmäki , A , Suur-Uski , A -S , Valiviita , J & Planck Collaboration 2015 , ' Planck intermediate results XXV : The Andromeda galaxy as seen by Planck ' , Astronomy & Astrophysics , vol. 582 , A28 , pp. A28 . https://doi.org/10.1051/0004-6361/201424643

Title: Planck intermediate results XXV : The Andromeda galaxy as seen by Planck
Author: Ade, P. A. R.; Juvela, M.; Keihänen, E.; Kurki-Suonio, H.; Lähteenmäki, A.; Suur-Uski, A. -S.; Valiviita, J.; Planck Collaboration
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Date: 2015-10
Language: eng
Number of pages: 23
Belongs to series: Astronomy & Astrophysics
ISSN: 1432-0746
URI: http://hdl.handle.net/10138/233350
Abstract: The Andromeda galaxy (M 31) is one of a few galaxies that has sufficient angular size on the sky to be resolved by the Planck satellite. Planck has detected M 31 in all of its frequency bands, and has mapped out the dust emission with the High Frequency Instrument, clearly resolving multiple spiral arms and sub-features. We examine the morphology of this long-wavelength dust emission as seen by Planck, including a study of its outermost spiral arms, and investigate the dust heating mechanism across M 31. We find that dust dominating the longer wavelength emission (greater than or similar to 0.3 mm) is heated by the diffuse stellar population (as traced by 3.6 mu m emission), with the dust dominating the shorter wavelength emission heated by a mix of the old stellar population and star-forming regions (as traced by 24 mu m emission). We also fit spectral energy distributions for individual 5' pixels and quantify the dust properties across the galaxy, taking into account these different heating mechanisms, finding that there is a linear decrease in temperature with galactocentric distance for dust heated by the old stellar population, as would be expected, with temperatures ranging from around 22 K in the nucleus to 14 K outside of the 10 kpc ring. Finally, we measure the integrated spectrum of the whole galaxy, which we find to be well-fitted with a global dust temperature of (18.2 +/- 1.0) K with a spectral index of 1.62 +/- 0.11 (assuming a single modified blackbody), and a significant amount of free-free emission at intermediate frequencies of 20-60 GHz, which corresponds to a star formation rate of around 0.12 M-circle dot yr(-1). We find a 2.3 sigma detection of the presence of spinning dust emission, with a 30 GHz amplitude of 0.7 +/- 0.3 Jy, which is in line with expectations from our Galaxy.
Subject: galaxies: individual: Messier 31
galaxies: structure
galaxies: ISM
submillimeter: galaxies
radio continuum: galaxies
MULTIBAND IMAGING PHOTOMETER
RADIO-CONTINUUM SURVEY
PRE-LAUNCH STATUS
SPITZER-SPACE-TELESCOPE
FAR-INFRARED LUMINOSITY
SPINNING DUST EMISSION
RESOLUTION IRAS MAPS
STAR-FORMATION RATES
LOCAL GROUP GALAXIES
COMPLETE CO SURVEY
115 Astronomy, Space science
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