{
  "id": "2006.14976",
  "version": "v1",
  "published": "2020-06-26T13:20:56.000Z",
  "updated": "2020-06-26T13:20:56.000Z",
  "title": "Kink-driven magnetic reconnection in relativistic jets: consequences for X-ray polarimetry of BL Lacs",
  "authors": [
    "Gianluigi Bodo",
    "Fabrizo Tavecchio",
    "Lorenzo Sironi"
  ],
  "comment": "12 pages, 14 figures, submitted to MNRAS",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We investigate with relativistic MHD simulations the dissipation physics of BL Lac jets, by studying the synchrotron polarization signatures of particles accelerated by the kink instability in a magnetically-dominated plasma column. The nonlinear stage of the kink instability generates current sheets, where particles can be efficiently accelerated via magnetic reconnection. We identify current sheets as regions where s = J d/B is above some predefined threshold (where B is the field strength, J the current density and d the grid scale), and assume that the particle injection efficiency scales as proportional to the square of the current. X-ray emitting particles have short cooling times, so they only probe the field geometry of their injection sites. In contrast, particles emitting in the optical band, which we follow self-consistently as they propagate away from their injection sites while cooling, sample a larger volume, and so they may be expected to produce different polarimetric signatures. We find that the degree of polarization is roughly the same between X-ray and optical bands, because even the optical-emitting particles do not travel far from the current sheet where they were injected, due to lack of sufficient kink-generated turbulence. The polarization angle shows a different temporal evolution between the two bands, due to the different regions probed by X-ray and optical emitting particles. In view of the upcoming IXPE satellite, our results can help constrain whether kink-induced reconnection (as opposed to shocks) can be the source of multi-wavelength emission from BL Lacs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-06-26T13:20:56.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "bl lac",
      "kink-driven magnetic reconnection",
      "relativistic jets",
      "x-ray polarimetry",
      "kink instability generates current sheets"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}