{
  "id": "1604.07402",
  "version": "v1",
  "published": "2016-04-25T20:00:00.000Z",
  "updated": "2016-04-25T20:00:00.000Z",
  "title": "The IRX-$β$ relation: Insights from simulations",
  "authors": [
    "Mohammadtaher Safarzadeh",
    "Christopher C. Hayward",
    "Henry C. Ferguson"
  ],
  "comment": "13 pages+a 4-page appendix, submitted to ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We study the relationship between the UV continuum slope and infrared excess (IRX$\\equiv L_{\\rm IR}/L_{\\rm FUV}$) predicted by performing dust radiative transfer on a suite of hydrodynamical simulations of galaxies. Our suite includes both isolated disk galaxies and mergers intended to be representative of galaxies at both $z \\sim 0$ and $z \\sim 2-3$. Our low-redshift isolated disks and mergers often populate a region around the the locally calibrated \\citet[][M99]{M99} relation but move well above the relation during merger-induced starbursts. Our high-redshift simulated galaxies are blue and IR-luminous, which makes them lie above the M99 relation. The value of UV continuum slope strongly depends on the dust type used in the radiative transfer calculations: Milky Way-type dust leads to significantly more negative (bluer) slopes compared with Small Magellanic Cloud-type dust. The effect on $\\beta$ due to variations in the dust composition with galaxy properties or redshift can dominate over other sources of $\\beta$ variations and is the dominant model uncertainty. The dispersion in $\\beta$ is anticorrelated with specific star formation rate and tends to be higher for the $z \\sim 2-3$ simulations. In the actively star-forming $z \\sim 2-3$ simulated galaxies, dust attenuation dominates the dispersion in $\\beta$, whereas in the $z \\sim 0$ simulations, the contributions of SFH variations and dust are similar. For low-SSFR systems at both redshifts, SFH variations dominate the dispersion. Finally, the simulated $z \\sim 2-3$ isolated disks and mergers both occupy a region in the \\irxbeta\\ plane consistent with observed $z \\sim 2-3$ dusty star-forming galaxies (DSFGs). Thus, contrary to some claims in the literature, the blue colors of high-z DSFGs do not imply that they are short-lived starbursts.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-04-25T20:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "simulations",
      "uv continuum slope",
      "isolated disk",
      "small magellanic cloud-type dust",
      "specific star formation rate"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 13,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016arXiv160407402S"
    }
  }
}