{
  "id": "1711.07598",
  "version": "v1",
  "published": "2017-11-21T01:38:05.000Z",
  "updated": "2017-11-21T01:38:05.000Z",
  "title": "Revisiting LS I +61 303 with VLBI astrometry",
  "authors": [
    "Y. W. Wu",
    "G. Torricelli-Ciamponi",
    "M. Massi",
    "M. J. Reid",
    "B. Zhang",
    "L. Shao",
    "X. W. Zheng"
  ],
  "comment": "10 pages, 10 Figures, 1 Table, MNRAS accepted 2017 November 19",
  "categories": [
    "astro-ph.GA",
    "astro-ph.HE"
  ],
  "abstract": "We conducted multi-epoch VLBA phase reference observations of LS I +61 303 in order to study its precessing radio jet. Compared to similar observations in 2006, we find that the observed elliptical trajectory of emission at 8.4 GHz repeats after the 9-year gap. The accurate alignment of the emission patterns yields a precession period of 26.926 +- 0.005 d, which is consistent with that determined by Lomb-Scargle analysis of the radio light curve. We analytically model the projection on the sky plane of the peak position of a precessing, synchrotron-emitting jet, which traces an elliptical trajectory on the sky. Comparing the simulation with the VLBA astrometry we improve our knowledge of the geometry of the system.We measure the LS I +61 303 absolute proper motion to be -0.150 +- 0.006 mas/yr eastward and -0.264 +- 0.006 mas/yr northward. Removing Galactic rotation, this reveals a small, < 20 km/s, non-circular motion, which indicates a very low kick velocity when the black hole was formed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-11-21T01:38:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "vlbi astrometry",
      "revisiting ls",
      "multi-epoch vlba phase reference observations",
      "conducted multi-epoch vlba phase reference",
      "elliptical trajectory"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}