{
  "id": "1506.05723",
  "version": "v1",
  "published": "2015-06-18T15:45:05.000Z",
  "updated": "2015-06-18T15:45:05.000Z",
  "title": "Constraints of Flat Spectrum Radio Quasars in the hadronic model: the case of 3C 273",
  "authors": [
    "Maria Petropoulou",
    "Stavros Dimitrakoudis"
  ],
  "comment": "14 pages, 8 figures, MNRAS accepted",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We present a method of constraining the properties of the $\\gamma$-ray emitting region in flat spectrum radio quasars (FSRQs) in the one-zone proton synchrotron model, where the $\\gamma$-rays are produced by synchrotron radiation of relativistic protons. We show that for low enough values of the Doppler factor $\\delta$, the emission from the electromagnetic (EM) cascade which is initiated by the internal absorption of high-energy photons from photohadronic interactions may exceed the observed $\\sim$GeV flux. We use that effect to derive an absolute lower limit of $\\delta$; first, an analytical one, in the asymptotic limit where the external radiation from the broad line region (BLR) is negligible, and then a numerical one in the more general case that includes BLR radiation. As its energy density in the emission region depends on $\\delta$ and the region's distance from the galactic center, we use the EM cascade to determine a minimum distance for each value of $\\delta$. We complement the EM cascade constraint with one derived from variability arguments and apply our method to the FSRQ 3C 273. We find that $\\delta \\gtrsim 18-20$ for $B \\lesssim 30$ G and $\\sim$day timescale variability; the emission region is located outside the BLR, namely at $r \\gtrsim 10 R_{\\rm BLR} \\sim 3$ pc; the model requires at pc-scale distances stronger magnetic fields than those inferred from core shift observations; while the jet power exceeds by at least one order of magnitude the accretion power. In short, our results disfavour the proton synchrotron model for the FSRQ 3C 273.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-06-18T15:45:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "flat spectrum radio quasars",
      "hadronic model",
      "proton synchrotron model",
      "pc-scale distances stronger magnetic fields",
      "constraint"
    ],
    "publication": {
      "doi": "10.1093/mnras/stv1380"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1376926
    }
  }
}