{
  "id": "1705.02721",
  "version": "v1",
  "published": "2017-05-08T01:35:19.000Z",
  "updated": "2017-05-08T01:35:19.000Z",
  "title": "Origin of X-rays in the low state of the FSRQ 3C 273: Evidence of inverse Compton emission",
  "authors": [
    "Nibedita Kalita",
    "Alok C. Gupta",
    "Paul J. Wiita",
    "Gulab C. Dewangan",
    "Kalpana Duorah"
  ],
  "comment": "17 pages, 8 figures, 3 tables; Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We analyze the 2.5--10 keV X-ray spectra of the luminous quasar 3C 273 and simultaneous observations in UV wavelengths from XMM--Newton between 2000 and 2015. The lowest flux level ever was observed in 2015. The continuum emission from 3C 273 is generally best described by an absorbed power-law but during extremely low states the addition of fluorescence from the K-shell iron line improves the fit. We study the spectral evolution of the source during its extended quiescent state and also examine connections between the X-ray and ultraviolet emissions, which have been seen in some, but not all, previous work. We detect a possible anti-correlation between these two bands during the low state that characterized 3C 273 for most of this period; however, this was not present during a flaring state. A harder-when-brighter trend for the X-ray spectrum was observed in these long-term observations of 3C 273 for the first time. We suggest that the X-ray emission in 3C 273 is the result of inverse Compton scattering of soft UV seed photons (emitted from the local environment of the AGN), most likely in a thermal corona. We can explain the significant temporal variation of the spectral continuum as an outcome of changing optical depth of the comptonizing medium, along the lines of the wind-shock model proposed by Courvoisier and Camenzind (1989).",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-05-08T01:35:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "inverse compton emission",
      "low state",
      "fsrq 3c",
      "x-ray spectrum",
      "kev x-ray spectra"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}