Volume 586, February 2016
|Number of page(s)||13|
|Published online||20 January 2016|
The bolometric and UV attenuation in normal spiral galaxies of the Herschel Reference Survey⋆
Sterrenkundig Observatorium, Universiteit Gent,
Krijgslaan 281, 9000
2 UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
3 Unidad de Astronoma, Fac. de Ciencias Bsicas, Universidad de Antofagasta, 02800 Antofagasta, Chile
4 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
5 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
6 Laboratoire AIM, CEA/DSM–CNRS–Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
7 International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
8 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
9 School of Physics & Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA, UK
10 Instituto de Radioastronomía y Astrofísica, UNAM, Antigua Carretera a Pátzcuaro # 8701, Morelia, Michoacán, Mexico
11 Istituto di Fisica dello Spazio Interplanetario, INAF, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
Received: 17 October 2015
Accepted: 18 November 2015
The dust in nearby galaxies absorbs a fraction of the UV-optical-near-infrared radiation produced by stars. This energy is consequently re-emitted in the infrared. We investigate the portion of the stellar radiation absorbed by spiral galaxies from the Herschel Reference Survey (HRS) by modelling their UV-to-submillimetre spectral energy distributions. Our models provide an attenuated and intrinsic spectral energy distribution (SED), from which we find that on average 32% of all starlight is absorbed by dust. We define the UV heating fraction as the percentage of dust luminosity that comes from absorbed UV photons and find this to be 56%, on average. This percentage varies with morphological type, with later types having significantly higher UV heating fractions. We find a strong correlation between the UV heating fraction and specific star formation rate and provide a power-law fit. Our models allow us to revisit the IRX – AFUV relations, and derive these quantities directly within a self-consistent framework. We calibrate this relation for different bins of NUV − r colour and provide simple relations to relate these parameters. We investigated the robustness of our method and conclude that the derived parameters are reliable within the uncertainties that are inherent to the adopted SED model. This calls for a deeper investigation of how well extinction and attenuation can be determined through panchromatic SED modelling.
Key words: Galaxy: fundamental parameters / galaxies: ISM / dust, extinction / infrared: ISM
© ESO, 2016
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