{
  "id": "2104.10702",
  "version": "v1",
  "published": "2021-04-21T18:01:46.000Z",
  "updated": "2021-04-21T18:01:46.000Z",
  "title": "Chandra Observations of Excess Fe K$α$ Line Emission in Galaxies with High Star Formation Rates: X-ray Reflection on Galaxy Scales?",
  "authors": [
    "Wei Yan",
    "Ryan C. Hickox",
    "Chien-Ting J. Chen",
    "Claudio Ricci",
    "Alberto Masini",
    "Franz E. Bauer",
    "David M. Alexander"
  ],
  "comment": "8 pages, 5 figures, accepted by ApJ",
  "categories": [
    "astro-ph.GA",
    "astro-ph.HE"
  ],
  "abstract": "In active galactic nuclei (AGN), fluorescent Fe K$\\alpha$ (iron) line emission is generally interpreted as originating from obscuring material around a supermassive black hole (SMBH) on the scale of a few parsecs (pc). However, recent Chandra studies indicate the existence of iron line emission extending to kpc scales in the host galaxy. The connection between iron line emission and large-scale material can be spatially resolved directly only in nearby galaxies, but could be inferred in more distant AGNs by a connection between line emission and star-forming gas and dust that is more extended than the pc-scale torus. Here we present the results from a stacking analysis and X-ray spectral fitting performed on sources in the Chandra Deep Field South (CDFS) 7 Ms observations. From the deep stacked spectra, we select sources with stellar mass $\\log(M_*/M_\\odot)>10$ at $0.5<z<2$, obtaining 25 sources with high infrared luminosity ($ {\\rm SFR}_{\\rm FIR} \\geq 17\\;M_{\\odot}\\;{\\rm yr}^{-1}$) and 32 sources below this threshold. We find that the equivalent width of the iron line EW(Fe) is a factor of three higher with 3$\\sigma$ significance for high infrared luminosity measured from Herschel observations, indicating a connection between iron line emission and star-forming material on galaxy scales. We show that there is no significant dependence in EW(Fe) on $M_*$ or X-ray luminosity, suggesting the reflection of AGN X-ray emission over large scales in their host galaxies may be widespread.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-04-21T18:01:46.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high star formation rates",
      "galaxy scales",
      "iron line emission",
      "excess fe",
      "x-ray reflection"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}