{
  "id": "1602.07695",
  "version": "v1",
  "published": "2016-02-24T21:00:05.000Z",
  "updated": "2016-02-24T21:00:05.000Z",
  "title": "Lyman Alpha Signatures from Direct Collapse Black Holes",
  "authors": [
    "Mark Dijkstra",
    "Max Gronke",
    "David Sobral"
  ],
  "comment": "16 pages, 7 figures, submitted to ApJ following revision based on referee report",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "`Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z~7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. We find that gravitational heating of the collapsing cloud gives rise to a Lya cooling luminosity of up to ~ 1e38(M_gas/1e6 Msun)^2 erg/s. The Lya production rate can be significantly larger during the final stages of collapse, but collisional deexcitation efficiently suppresses the emerging Lya flux. Photoionization by a central source boosts the Lya luminosity to L~1e43(M_BH/1e6 M_sun) erg/s during specific evolutionary stages of the cloud, where M_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitter at z~7, which is potentially associated with a DCBH. If CR7 is powered by a black hole, then its Lya flux alone requires that M_BH> 1e7 M_sun, which exceeds the mass of DCBHs when they first form. The observed width of the Lya spectrum favors the presence of only a low column density of hydrogen, log [N_HI/cm^-2]~19-20. The shape of the Lya spectrum indicates that this gas is outflowing. These requirements imply that if CR7 harbors a DCBH, then the physical conditions that enabled its formation have been mostly erased, which is in agreement with theoretical expectations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-02-24T21:00:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "direct collapse black holes",
      "lyman alpha signatures",
      "lya spectral line range",
      "lya spectrum",
      "lya flux"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016arXiv160207695D",
      "inspire": 1424206
    }
  }
}