{
  "id": "1608.07584",
  "version": "v1",
  "published": "2016-08-26T20:00:38.000Z",
  "updated": "2016-08-26T20:00:38.000Z",
  "title": "Being WISE II: Reducing the Influence of Star Formation History on the Mass-to-Light Ratio of Quiescent Galaxies",
  "authors": [
    "Mark A. Norris",
    "Glenn Van de Ven",
    "Eva Schinnerer",
    "Robert A. Crain",
    "Sharon Meidt",
    "Brent Groves",
    "Richard G. Bower",
    "Michelle Furlong",
    "Matthieu Schaller",
    "Joop Schaye",
    "Tom Theuns"
  ],
  "comment": "15 pages, 11 figures. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Stellar population synthesis models can now reproduce the photometry of old stellar systems (age $>$ 2 Gyr) in the near-infrared (NIR) bands at 3.4 and 4.6$\\mu$m (WISE W1 $\\&$ W2 or IRAC 1 $\\&$ 2). In this paper we derive stellar mass-to-light ratios for these and optical bands, and confirm that the NIR M/L shows dramatically reduced sensitivity to both age and metallicity compared to optical bands, and further, that this behavior leads to significantly more robust stellar masses for quiescent galaxies with [Fe/H] > -0.5 regardless of star formation history (SFH). We then use realistic early-type galaxy SFHs and metallicity distributions from the EAGLE simulations of galaxy formation to investigate two methods to determine the appropriate M/L for a galaxy: 1) We show that the uncertainties introduced by an unknown SFH can be largely removed using a spectroscopically inferred luminosity-weighted age and metallicity for the population to select the appropriate single stellar population (SSP) equivalent M/L. Using this method, the maximum systematic error due to SFH on the M/L of an early-type galaxy is $<$ 4$\\%$ at 3.4 $\\mu$m and typical uncertainties due to errors in the age and metallicity create scatter of $\\lesssim$13$\\%$. The equivalent values for optical bands are more than 2-3 times greater, even before considering uncertainties associated with internal dust extinction. 2) We demonstrate that if the EAGLE SFHs and metallicities accurately reproduce the true properties of early-type galaxies, the use of an iterative approach to select a mass dependent M/L can provide even more accurate stellar masses for early-type galaxies, with typical uncertainties $<$ 9$\\%$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-08-26T20:00:38.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "star formation history",
      "mass-to-light ratio",
      "quiescent galaxies",
      "optical bands",
      "metallicity"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}