{
  "id": "1903.05121",
  "version": "v1",
  "published": "2019-03-12T18:11:38.000Z",
  "updated": "2019-03-12T18:11:38.000Z",
  "title": "A Universal Relation of Dust Obscuration Across Cosmic Time",
  "authors": [
    "Jianbo Qin",
    "X. Z. Zheng",
    "Stijn Wuyts",
    "Zhizheng Pan",
    "Jian Ren"
  ],
  "comment": "22 pages, 14 figures, accepted for publication in the MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We investigate dust obscuration as parameterised by the infrared excess IRX$\\equiv$$L_{\\rm IR}/L_{\\rm UV}$ in relation to global galaxy properties, using a sample of $\\sim$32$\\,$000 local star-forming galaxies (SFGs) selected from SDSS, GALEX and WISE. We show that IRX generally correlates with stellar mass ($M_\\ast$), star formation rate (SFR), gas-phase metallicity ($Z$), infrared luminosity ($L_{\\rm IR}$) and the half-light radius ($R_{\\rm e}$). A weak correlation of IRX with axial ratio (b/a) is driven by the inclination and thus seen as a projection effect. By examining the tightness and the scatter of these correlations, we find that SFGs obey an empirical relation of the form $IRX$=$10^\\alpha\\,(L_{\\rm IR})^{\\beta}\\,R_{\\rm e}^{-\\gamma}\\,(b/a)^{-\\delta}$ where the power-law indices all increase with metallicity. The best-fitting relation yields a scatter of $\\sim$0.17$\\,$dex and no dependence on stellar mass. Moreover, this empirical relation also holds for distant SFGs out to $z=3$ in a population-averaged sense, suggesting it to be universal over cosmic time. Our findings reveal that IRX approximately increases with $L_{\\rm IR}/R_{\\rm e}^{[1.3 - 1.5]}$ instead of $L_{\\rm IR}/R_{\\rm e}^{2}$ (i.e., surface density). We speculate this may be due to differences in the spatial extent of stars versus star formation and/or complex star-dust geometries. We conclude that not stellar mass but IR luminosity, metallicity and galaxy size are the key parameters jointly determining dust obscuration in SFGs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-03-12T18:11:38.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "cosmic time",
      "universal relation",
      "parameters jointly determining dust obscuration",
      "complex star-dust geometries",
      "surface density"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}