Linking dust emission to fundamental properties in galaxies: the low-metallicity picture⋆
Institut d’Astrophysique Spatiale, CNRS, UMR 8617,
e-mail: firstname.lastname@example.org; email@example.com
2 Laboratoire AIM, CEA/IRFU/Service d’Astrophysique, Université Paris Diderot, Bât. 709, 91191 Gif-sur-Yvette, France
3 Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
4 UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
5 Laboratoire d’Astrophysique de Marseille – LAM, Université d’Aix-Marseille & CNRS, UMR 7326, 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France
6 Department of Physics, University of Crete, 71003 Heraklion, Greece
7 Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany
8 Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
9 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, Mail H30, PO Box 218, Hawthorn VIC 3122, Australia
10 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
11 Max-Planck für Extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching-bei-München, Germany
12 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching-bei-München, Germany
13 Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK
14 NASA Herschel Science Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125, USA
15 Instituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via Fosso del Cavaliere 100, 00133 Roma, Italy
Received: 10 March 2015
Accepted: 14 July 2015
Aims. In this work, we aim to provide a consistent analysis of the dust properties from metal-poor to metal-rich environments by linking them to fundamental galactic parameters.
Methods. We consider two samples of galaxies: the Dwarf Galaxy Survey (DGS) and the Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH), totalling 109 galaxies, spanning almost 2 dex in metallicity. We collect infrared (IR) to submillimetre (submm) data for both samples and present the complete data set for the DGS sample. We model the observed spectral energy distributions (SED) with a physically-motivated dust model to access the dust properties: dust mass, total-IR luminosity, polycyclic aromatic hydrocarbon (PAH) mass fraction, dust temperature distribution, and dust-to-stellar mass ratio.
Results. Using a different SED model (modified black body), different dust composition (amorphous carbon in lieu of graphite), or a different wavelength coverage at submm wavelengths results in differences in the dust mass estimate of a factor two to three, showing that this parameter is subject to non-negligible systematic modelling uncertainties. We find half as much dust with the amorphous carbon dust composition. For eight galaxies in our sample, we find a rather small excess at 500 μm (≤1.5σ). We find that the dust SED of low-metallicity galaxies is broader and peaks at shorter wavelengths compared to more metal-rich systems, a sign of a clumpier medium in dwarf galaxies. The PAH mass fraction and dust temperature distribution are found to be driven mostly by the specific star formation rate, sSFR, with secondary effects from metallicity. The correlations between metallicity and dust mass or total-IR luminosity are direct consequences of the stellar mass-metallicity relation. The dust-to-stellar mass ratios of metal-rich sources follow the well-studied trend of decreasing ratio for decreasing sSFR. The relation is more complex for low-metallicity galaxies with high sSFR, and depends on the chemical evolutionary stage of the source (i.e. gas-to-dust mass ratio). Dust growth processes in the ISM play a key role in the dust mass build-up with respect to the stellar content at high sSFR and low metallicity.
Conclusions. We conclude that the evolution of the dust properties from metal-poor to metal-rich galaxies derives from a complex interplay between star formation activity, stellar mass, and metallicity.
Key words: dust, extinction / evolution / galaxies: dwarf / galaxies: evolution / infrared: ISM / infrared: galaxies
Figures 12 and 13, Tables 4–9, and Appendices are available in electronic form at http://www.aanda.org
© ESO, 2015