Volume 637, May 2020
|Number of page(s)||23|
|Published online||07 May 2020|
High-resolution, 3D radiative transfer modelling
III. The DustPedia barred galaxies
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 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
5 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
6 INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 4019 Bologna, Italy
7 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MA 21218, USA
8 School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
9 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
10 Instituto de Radioastronomía y Astrofísica, UNAM, Campus Morelia, AP 3-72, 58089 Michoacán, Mexico
11 Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
12 Institut d’Astrophysique Spatiale, UMR 8617, CNRS, Université Paris Sud, Université Paris-Saclay, Université Paris Sud, Orsay 91405, France
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
Accepted: 24 July 2019
Context. Dust in late-type galaxies in the local Universe is responsible for absorbing approximately one third of the energy emitted by stars. It is often assumed that dust heating is mainly attributable to the absorption of ultraviolet and optical photons emitted by the youngest (≤100 Myr) stars. Consequently, thermal re-emission by dust at far-infrared wavelengths is often linked to the star-formation activity of a galaxy. However, several studies argue that the contribution to dust heating by much older stellar populations might be more significant than previously thought. Advances in radiation transfer simulations finally allow us to actually quantify the heating mechanisms of diffuse dust by the stellar radiation field.
Aims. As one of the main goals in the DustPedia project, we have developed a framework to construct detailed 3D stellar and dust radiative transfer models for nearby galaxies. In this study, we analyse the contribution of the different stellar populations to the dust heating in four nearby face-on barred galaxies: NGC 1365, M 83, M 95, and M 100. We aim to quantify the fraction directly related to young stellar populations, both globally and on local scales, and to assess the influence of the bar on the heating fraction.
Methods. From 2D images we derive the 3D distributions of stars and dust. To model the complex geometries, we used SKIRT, a state-of-the-art 3D Monte Carlo radiative transfer code designed to self-consistently simulate the absorption, scattering, and thermal re-emission by the dust for arbitrary 3D distributions.
Results. We derive global attenuation laws for each galaxy and confirm that galaxies of high specific star-formation rate have shallower attenuation curves and weaker UV bumps. On average, 36.5% of the bolometric luminosity is absorbed by dust in our galaxy sample. We report a clear effect of the bar structure on the radial profiles of the dust-heating fraction by the young stellar populations, and the dust temperature. We find that the young stellar populations are the main contributors to the dust heating, donating, on average ∼59% of their luminosity to this purpose throughout the galaxy. This dust-heating fraction drops to ∼53% in the bar region and ∼38% in the bulge region where the old stars are the dominant contributors to the dust heating. We also find a strong link between the heating fraction by the young stellar populations and the specific star-formation rate.
Key words: radiative transfer / dust, extinction / galaxies: ISM / infrared: ISM
© ESO 2019
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