Molecular gas, dust, and star formation in galaxies

I. Dust properties and scalings in ~1600 nearby galaxies

¹ Department of Astronomy, Universidad de Concepción, Casilla 160-C Concepción, Chile
e-mail: gorellana@udec.cl, gustavo.orellana@uv.cl
² Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile
³ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Université Paris Diderot, Saclay, pt courrier 131, 91191 Gif-sur-Yvette, France
⁴ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁵ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago, Chile
⁶ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, 19 Santiago, Chile
⁷ Departamento de Ciencias Fisicas, Universidad Andres Bello, Sede Concepcion, autopista Concepcion-Talcahuano 7100, Talcahuano, Chile

Received: 25 May 2016
Accepted: 28 March 2017

Abstract

Context. Dust and its emission is increasingly being used to constrain the evolutionary stage of a galaxy. A comprehensive characterization of dust, best achieved in nearby bright galaxies, is thus a highly useful resource.

Aims. We aim to characterize the relationship between dust properties (mass, luminosity, and temperature) and their relationships with galaxy-wide properties (stellar, atomic, and molecular gas mass, and star formation mode). We also aim to provide equations to accurately estimate dust properties from limited observational datasets.

Methods. We assemble a sample of 1630 nearby (z < 0.1) galaxies – over a large range of stellar masses (M_∗), star formation rates (SFR) and specific star formation rates (sSFR = SFR/M_∗) – for which comprehensive and uniform multi-wavelength observations are available from WISE, IRAS, Planck, and/or SCUBA. The characterization of dust emission comes from spectral energy distribution (SED) fitting using Draine & Li (2007, ApJ, 657, 810) dust models, which we parametrize using two components (warm at 45–70 K and cold at 18–31 K). The subsample of these galaxies with global measurements of CO and/or HI are used to explore the molecular and/or atomic gas content of the galaxies.

Results. The total infrared luminosity (L_IR), dust mass (M_dust), and dust temperature of the cold component (T_cold) form a plane that we refer to as the dust plane. A galaxy’s sSFR drives its position on the dust plane: starburst (high sSFR) galaxies show higher L_IR , M_dust , and T_cold compared to main sequence (typical sSFR) and passive galaxies (low sSFR). Starburst galaxies also show higher specific dust masses (M_dust/M_∗) and specific gas masses (M_gas/M_∗). We confirm earlier findings of an anti-correlation between the dust to stellar mass ratio and M_∗ . We also find different anti-correlations depending on sSFR; the anti-correlation becomes stronger as the sSFR increases, with the spread due to different cold dust temperatures. The dust mass is more closely correlated with the total gas mass (atomic plus molecular) than with the individual atomic and molecular gas masses. Our comprehensive multiwavelength data allows us to define several equations to accurately estimate L_IR , M_dust , and T_cold from one or two monochromatic luminosities in the infrared and/or sub-millimeter.

Conclusions. It is possible to estimate the dust mass and infrared luminosity from a single monochromatic luminosity within the Rayleigh-Jeans tail of the dust emission, with errors of 0.12 and 0.20 dex, respectively. These errors are reduced to 0.05 and 0.10 dex, respectively, if the dust temperature of the cold component is used. The dust mass is better correlated with the total ISM mass (M_ISM ∝M_dust^0.7). For galaxies with stellar masses 8.5 < log(M_∗/M_⊙) < 11.9, the conversion factor between the single monochromatic luminosity at 850 μm and the total ISM mass (α_{850 μm}) shows a large scatter (rms = 0.29 dex) and a weak correlation with the L_IR . The star formation mode of a galaxy shows a correlation with both the gas mass and dust mass: the dustiest (high M_dust /M_∗) galaxies are gas-rich and show the highest SFRs.