{
  "id": "1712.09224",
  "version": "v1",
  "published": "2017-12-26T09:51:46.000Z",
  "updated": "2017-12-26T09:51:46.000Z",
  "title": "Magnetic field amplification by the r-mode instability",
  "authors": [
    "Andrey I. Chugunov",
    "John L. Friedman",
    "Lee Lindblom",
    "Luciano Rezzolla"
  ],
  "comment": "5 pages; Contribution to the proceedings of the Physics of Neutron Stars - 2017 (Saint Petersburg, July 10-14, 2017), associated with a talk by A.I. Chugunov",
  "journal": "J. Phys.: Conf. Ser. 932 012045 (2017)",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We discuss magnetic field enhancement by unstable r-modes (driven by the gravitational radiation reaction force) in rotating stars. In the absence of a magnetic field, gravitational radiation exponentially increases the r-mode amplitude $\\alpha$, and accelerates differential rotation (secular motion of fluid elements). For a magnetized star, differential rotation enhances the magnetic field energy. Rezzolla et al. (2000--2001) argued that if the magnetic energy grows faster than the gravitational radiation reaction force pumps energy into the r-modes, then the r-mode instability is suppressed. Chugunov (2015) demonstrated that without gravitational radiation, differential rotation can be treated as a degree of freedom decoupled from the r-modes and controlled by the back reaction of the magnetic field. In particular, the magnetic field windup does not damp r-modes. Here we discuss the effect of the back reaction of the magnetic field on differential rotation of unstable r-modes, and show that it limits the generated magnetic field and the magnetic energy growth rate preventing suppression of the r-mode instability by magnetic windup at low saturation amplitudes, $\\alpha \\ll 1$, predicted by current models.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-12-26T09:51:46.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "magnetic field amplification",
      "r-mode instability",
      "gravitational radiation reaction force",
      "radiation reaction force pumps",
      "differential rotation"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}