{
  "id": "1807.02869",
  "version": "v1",
  "published": "2018-07-08T19:27:31.000Z",
  "updated": "2018-07-08T19:27:31.000Z",
  "title": "On the multi-wavelength Emission from CTA 102",
  "authors": [
    "S. Gasparyan",
    "N. Sahakyan",
    "V. Baghmanyan",
    "D. Zargaryan"
  ],
  "comment": "Accepted for publication in ApJ",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We report on broadband observations of CTA 102 ($z=1.037$) during the active states in 2016-2017. In the $\\gamma$-ray band, Fermi LAT observed several prominent flares which followed a harder-when-brighter behavior: the hardest photon index $\\Gamma=1.61\\pm 0.10$ being unusual for FSRQs. The peak $\\gamma$-ray flux above 100 MeV $(3.55\\pm0.55)\\times10^{-5}\\:{\\rm photon\\:cm^{-2}\\:s^{-1}}$ observed on MJD 57738.47 within 4.31 minutes, corresponds to an isotropic $\\gamma$-ray luminosity of $L_{\\gamma}=3.25\\times10^{50}\\:{\\rm erg\\:s^{-1}}$, comparable with the highest values observed from blazars so far. The analyses of the Swift UVOT/XRT data show an increase in the UV/optical and X-ray bands which is contemporaneous with the bright $\\gamma$-ray periods. The X-ray spectrum observed by Swift XRT and NuSTAR during the $\\gamma$-ray flaring period is characterized by a hard photon index of $\\sim1.30$. The shortest e-folding time was $4.08\\pm1.44$ hours, suggesting a very compact emission region $R\\leq\\delta\\times2.16\\times10^{14}$ cm. We modeled the spectral energy distribution of CTA 102 in several periods (having different properties in UV/optical, X-ray and $\\gamma$-ray bands) assuming a compact blob inside and outside the BLR. We found that the high-energy data are better described when the infrared thermal radiation of the dusty torus is considered. In the flaring periods when the correlation between the $\\gamma$-ray and UV/optical/X-ray bands is lacking, the $\\gamma$-ray emission can be produced from the interaction of fresh electrons in a different blob, which does not make a dominant contribution at lower energies.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-07-08T19:27:31.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "multi-wavelength emission",
      "ray band",
      "spectral energy distribution",
      "compact emission region",
      "hard photon index"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}