{
  "id": "1903.01796",
  "version": "v1",
  "published": "2019-03-05T12:53:41.000Z",
  "updated": "2019-03-05T12:53:41.000Z",
  "title": "Direct observation of the Broad Line Region in X-rays during the low state of NGC4051",
  "authors": [
    "Uria Peretz",
    "Jon M. Miller",
    "Ehud Behar"
  ],
  "categories": [
    "astro-ph.GA",
    "astro-ph.HE"
  ],
  "abstract": "NGC 4051 is one of the X-ray brightest and most variable Seyfert galaxies. During 2009 NGC 4051 was caught at its lowest state ever observed by $XMM-Newton$. The low source continuum emission allows a clear measurement of the He-like emission lines of N$^{+5}$ and O$^{+6}$. The exceptionally high intercombination line flux is a direct measurement of either a high density or a UV irradiated photoionized plasma. Either way, this provides an unambiguous distance diagnostic. We find that the line emitting region has a density of $\\sim3\\times10^{10}$ cm$^{-3}$ and distance of a few $10^{15}$ cm from the continuum source, placing it within the UV-optical Broad Line Region of NGC 4051. Both N$^{+5}$ and O$^{+6}$ independently result in similar measurements for density and distance. In addition, we find the kinematics of the broad O$^{+7}$ Ly$\\alpha$ match those of the He$^{+1}\\,\\lambda4686$\\,\\AA\\ line, which is associated with the NGC 4051 Broad Line Region. This is the first direct X-ray measurement of a Seyfert Broad Line Region.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-03-05T12:53:41.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "direct observation",
      "low state",
      "first direct x-ray measurement",
      "seyfert broad line region",
      "exceptionally high intercombination line flux"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}