{
  "id": "2005.06178",
  "version": "v1",
  "published": "2020-05-13T06:43:45.000Z",
  "updated": "2020-05-13T06:43:45.000Z",
  "title": "The optical polarization of the blazar PKS 2155$-$304 during an optical flare in 2010",
  "authors": [
    "N. W. Peceur",
    "A. R. Taylor",
    "R. C. Kraan-Korteweg"
  ],
  "comment": "8 pages, 9 figures",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "An analysis is presented of the optical polarimetric and multicolour photometric ($BVRJ$) behaviour of the blazar PKS 2155$-$304 during an outburst in 2010. This flare develops over roughly 117 days, with a flux doubling time $\\tau \\sim 4$ days that increases from blue to red wavelengths. The polarization angle is initially aligned with the jet axis but rotates by roughly $90^\\circ$ as the flare grows. Two distinct states are evident at low and high fluxes. Below 18 mJy, the polarization angle takes on a wide range of values, without any clear relation to the flux. In contrast, there is a positive correlation between the polarization angle and flux above 18 mJy. The polarization degree does not display a clear correlation with the flux. We find that the photopolarimetric behaviour for the high flux state can be attributed to a variable component with a steady power-law spectral energy distribution and high optical polarization degree (13.3%). These properties are interpreted within the shock-in-jet model, which shows that the observed variability can be explained by a shock that is seen nearly edge-on. Some parameters derived for the relativistic jet within the shock-in-jet model are: $B=0.09$ G for the magnetic field, $\\delta=22.3$ for the Doppler factor and $\\Phi=2.6^\\circ$ for the viewing angle.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-05-13T06:43:45.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "blazar pks",
      "optical flare",
      "polarization angle",
      "steady power-law spectral energy distribution",
      "shock-in-jet model"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}