{
  "id": "1509.04945",
  "version": "v1",
  "published": "2015-09-16T15:13:30.000Z",
  "updated": "2015-09-16T15:13:30.000Z",
  "title": "Parameter constraints in a near-equipartition model with multi-frequency \\emph{NuSTAR}, \\emph{Swift} and \\emph{Fermi-LAT} data from 3C 279",
  "authors": [
    "Dahai Yan",
    "Li Zhang",
    "Shuang-Nan Zhang"
  ],
  "comment": "accepted by MNRAS",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA"
  ],
  "abstract": "Precise spectra of 3C 279 in the 0.5-70 keV range, obtained during two epochs of \\emph{Swift} and \\emph{NuSTAR} observations, are analyzed using a near-equipartition model. We apply a one-zone leptonic model with a three-parameter log-parabola electron energy distribution (EED) to fit the \\emph{Swift} and \\emph{NuSTAR} X-ray data, as well as simultaneous optical and \\emph{Fermi}-LAT $\\gamma$-ray data. The Markov Chain Monte Carlo (MCMC) technique is used to search the high-dimensional parameter space and evaluate the uncertainties on model parameters. We show that the two spectra can be successfully fit in near-equipartition conditions, defined by the ratio of the energy density of relativistic electrons to magnetic field $\\zeta_{\\rm e}$ being close to unity. In both spectra, the observed X-rays are dominated by synchrotron-self Compton photons, and the observed $\\gamma$ rays are dominated by Compton scattering of external infrared photons from a surrounding dusty torus. Model parameters are well constrained. From the low state to the high state, both the curvature of the log-parabola width parameter and the synchrotron peak frequency significantly increase. The derived magnetic fields in the two states are nearly identical ($\\sim1$\\ G), but the Doppler factor in the high state is larger than that in the low state ($\\sim$28 versus $\\sim$18). We derive that the gamma-ray emission site takes place outside the broad-line region, at $\\gtrsim$ 0.1 pc from the black hole, but within the dusty torus. Implications for 3C 279 as a source of high-energy cosmic-rays are discussed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-09-16T15:13:30.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "near-equipartition model",
      "parameter constraints",
      "three-parameter log-parabola electron energy distribution",
      "markov chain monte carlo",
      "model parameters"
    ],
    "publication": {
      "doi": "10.1093/mnras/stv2091"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1393644
    }
  }
}