{
  "id": "1710.01251",
  "version": "v1",
  "published": "2017-10-03T16:16:51.000Z",
  "updated": "2017-10-03T16:16:51.000Z",
  "title": "Physical properties of 15 quasars at $z\\gtrsim 6.5$",
  "authors": [
    "C. Mazzucchelli",
    "E. Bañados",
    "B. P. Venemans",
    "R. Decarli",
    "E. P. Farina",
    "F. Walter",
    "A. -C. Eilers",
    "H. -W. Rix",
    "R. Simcoe",
    "D. Stern",
    "X. Fan",
    "E. Schlafly",
    "G. De Rosa",
    "J. Hennawi",
    "K. C. Chambers",
    "J. Greiner",
    "W. Burgett",
    "P. W. Draper",
    "N. Kaiser",
    "R. -P. Kudritzki",
    "E. Magnier",
    "N. Metcalfe",
    "C. Waters",
    "R. J. Wainscoat"
  ],
  "comment": "29 pages, 18 figures; accepted by ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only few quasars have been reported at $z > 6.5$ ($<$800 Myr after the Big Bang). In this work, we present six additional $z \\gtrsim 6.5$ quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 $z \\gtrsim 6.5$ quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of $z\\gtrsim$6.5 quasars show large blueshifts of the broad CIV 1549\\AA$\\,$emission line compared to the systemic redshift of the quasars, with a median value $\\sim$3$\\times$ higher than a quasar sample at $z\\sim$1; (2) we estimate the quasars' black hole masses (M$\\rm_{BH}\\sim$0.3$-$5 $\\times$ 10$^{9}$ M$_{\\odot}$) via modeling of the MgII 2798\\AA$\\,$emission line and rest-frame UV continuum; we find that quasars at high redshift accrete their material (with $\\langle (L_{\\mathrm{bol}}/L_{\\mathrm{Edd}}) \\rangle = 0.39$) at a rate comparable to a luminosity-matched sample at lower$-$redshift, albeit with significant scatter ($0.4$ dex); (3) we recover no evolution of the FeII/MgII abundance ratio with cosmic time; (4) we derive near zone sizes; together with measurements for $z\\sim6$ quasars from recent work, we confirm a shallow evolution of the decreasing quasar near zone sizes with redshift. Finally, we present new millimeter observations of the [CII] 158 $\\mu$m emission line and underlying dust continuum from NOEMA for four quasars, and provide new accurate redshifts and [CII]/infrared luminosities estimates. The analysis presented here shows the large range of properties of the most distant quasars.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-10-03T16:16:51.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "physical properties",
      "emission line",
      "accreting supermassive black holes",
      "hosting accreting supermassive black",
      "zone sizes"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 29,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}