{
  "id": "1509.08393",
  "version": "v1",
  "published": "2015-09-28T17:05:42.000Z",
  "updated": "2015-09-28T17:05:42.000Z",
  "title": "A Systematic Search for Changing-Look Quasars in SDSS",
  "authors": [
    "Chelsea L. MacLeod",
    "Nicholas P. Ross",
    "Andy Lawrence",
    "Mike Goad",
    "Keith Horne",
    "William Burgett",
    "Ken C. Chambers",
    "Heather Flewelling",
    "Klaus Hodapp",
    "Nick Kaiser",
    "Eugene Magnier",
    "Richard Wainscoat",
    "Christopher Waters"
  ],
  "comment": "15 pages, 8 Figures, 3 Tables, submitted to MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with large, $|\\Delta g|>1$~mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or \"changing-look'' BEL features. Four of our objects have emerging BELs; five have disappearing BELs, and one object shows tentative evidence for having both emerging and disappearing BELs. With redshifts in the range 0.20<z<0.63, this sample includes the highest-redshift changing-look quasars discovered to date. We highlight the quasar J102152.34+464515.6 at z=0.204. Here, not only have the Balmer emisson lines strongly diminished in prominence, including H\\beta all but disappearing, but the blue continuum f_{\\nu}\\propto \\nu^{1/3} typical of an AGN is also significantly diminished in the second epoch of spectroscopy. We test a simple dust-reddening toy model, and find that this is inadequate to explain the change in spectral properties of this object. Using our selection criteria, we estimate that >12% of luminous quasars that vary by |\\Delta g|>1 mag display changing-look BEL features on rest-frame timescales of 8 to 10 years. We discuss the possibilities for the origin of such BEL changes, such as a change in obscuration or in the central engine.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-09-28T17:05:42.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "changing-look quasars",
      "systematic search",
      "mag display changing-look bel features",
      "disappearing bels",
      "mag photometric variations"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}