{
  "id": "1803.01510",
  "version": "v1",
  "published": "2018-03-05T05:57:57.000Z",
  "updated": "2018-03-05T05:57:57.000Z",
  "title": "SED constraints on the highest-$z$ blazar jet: QSO J0906+6930",
  "authors": [
    "Hongjun An",
    "Roger W. Romani"
  ],
  "comment": "10 pages, 5 figures, 2 tables. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We report on Gemini, NuSTAR and 8-year Fermi observations of the most distant blazar QSO~J0906$+$6930 ($z=5.48$). We construct a broadband spectral energy distribution (SED) and model the SED using a synchro-Compton model. The measurements find a $\\sim 4 \\times 10^9 M_\\odot$ mass for the black hole and a spectral break at $\\sim$4 keV in the combined fit of the new NuSTAR and archival Chandra data. The SED fitting constrains the bulk Doppler factor $\\delta$ of the jet to $9^{+2.5}_{-3}$ for QSO~J0906$+$6930. Similar, but weaker $\\delta$ constraints are derived from SED modeling of the three other claimed $z>5$ blazars. Together, these extrapolate to $\\sim620$ similar sources, fully 20\\% of the optically bright, high mass AGN expected at $5<z<5.5$. This has interesting implications for the early growth of massive black holes.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-03-05T05:57:57.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "blazar jet",
      "sed constraints",
      "broadband spectral energy distribution",
      "archival chandra data",
      "high mass agn"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}