{
  "id": "1512.09015",
  "version": "v1",
  "published": "2015-12-30T17:05:28.000Z",
  "updated": "2015-12-30T17:05:28.000Z",
  "title": "A model for the polarization of the high-energy radiation from accreting black holes: the case of XTE J1118+480",
  "authors": [
    "Florencia L. Vieyro",
    "Gustavo E. Romero",
    "Sylvain Chaty"
  ],
  "comment": "8 pages, 6 figures, accepted for publication in A&A",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "The high-energy emission ($400$ keV $- 2$ MeV) of Cygnus X-1 --the most well-studied Galactic black hole-- was recently found to be strongly polarized. The origin of this radiation is still unknown. In this work, we suggest that it is the result of non-thermal processes in the hot corona around the accreting compact object, and study the polarization of high-energy radiation expected for black hole binaries. Two contributions to the total magnetic field are taken into account in our study, a small scale random component related to the corona, and an ordered magnetic field associated with the accretion disk. The degree of polarization of gamma-ray emission for this particular geometry is estimated, as well as the angle of the polarization vector. We obtain that the corona+disk configuration studied in this work can account for the high degree of polarization of gamma-rays detected in galactic black holes without the need of a relativistic jet; specific predictions are made for sources in a low-hard state. In particular, the model is applied to the transient source \\xtee; we show that if a new outburst of \\xte is observed, then its gamma-ray polarization should be measurable by future instruments, such as ASTRO-H or the proposed ASTROGAM.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-12-30T17:05:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "accreting black holes",
      "high-energy radiation",
      "polarization",
      "small scale random component",
      "galactic black holes"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/201526587"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1411602
    }
  }
}