Old and young stellar populations in DustPedia galaxies and their role in dust heating
National Observatory of Athens, Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, Ioannou Metaxa and Vasileos Pavlou, 15236 Athens, Greece
2 Department of Astrophysics, Astronomy & Mechanics, Faculty of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Athens, Greece
3 Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
4 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
5 Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, 91191 Gif-sur Yvette, France
6 Institut d’Astrophysique Spatiale, UMR 8617, CNRS, Université Paris Sud, Université Paris-Saclay, Université Paris Sud, 91405 Orsay, France
7 INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 4019 Bologna, Italy
8 INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica, Via Alfonso Corti 12, 20133 Milan, Italy
9 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
10 School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
11 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
12 Instituto de Radioastronomía y Astrofísica, UNAM, Campus Morelia, AP 3-72, 58089 Michoacán, Mexico
13 Central Astronomical Observatory of RAS, Pulkovskoye Chaussee 65/1, 196140 St. Petersburg, Russia
14 St. Petersburg State University, Universitetskij Pr. 28, 198504 St. Petersburg, Stary Peterhof, Russia
15 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
Accepted: 13 March 2019
Aims. Within the framework of the DustPedia project we investigate the properties of cosmic dust and its interaction with stellar radiation (originating from different stellar populations) for 814 galaxies in the nearby Universe, all observed by the Herschel Space Observatory.
Methods. We take advantage of the widely used fitting code CIGALE, properly adapted to include the state-of-the-art dust model THEMIS. For comparison purposes, an estimation of the dust properties is provided by approximating the emission at far-infrared and sub-millimeter wavelengths with a modified blackbody. Using the DustPedia photometry we determine the physical properties of the galaxies, such as the dust and stellar mass, the star-formation rate, the bolometric luminosity, the unattenuated and the absorbed by dust stellar light, for both the old (> 200 Myr) and young (≤200 Myr) stellar populations.
Results. We show how the mass of stars, dust, and atomic gas, as well as the star-formation rate and the dust temperature vary between galaxies of different morphologies and provide recipes to estimate these parameters given their Hubble stage (T). We find a mild correlation between the mass fraction of the small a-C(:H) grains with the specific star-formation rate. On average, young stars are very efficient in heating the dust, with absorption fractions reaching as high as ∼77% of the total unattenuated luminosity of this population. On the other hand, the maximum absorption fraction of old stars is ∼24%. Dust heating in early-type galaxies is mainly due to old stars, up to a level of ∼90%. Young stars progressively contribute more for “typical” spiral galaxies and they become the dominant source of dust heating for Sm-type and irregular galaxies, with ∼60% of their luminosity contributing to that purpose. Finally, we find a strong correlation of the dust heating fraction by young stars with morphology and the specific star-formation rate.
Key words: dust / extinction / infrared: galaxies / galaxies: photometry / galaxies: ISM / galaxies: evolution
© ESO 2019