{
  "id": "0912.3809",
  "version": "v1",
  "published": "2009-12-18T21:26:26.000Z",
  "updated": "2009-12-18T21:26:26.000Z",
  "title": "Discovery of a New Torque Reversal of the Accreting X-ray Pulsar 4U 1626-67 by Fermi/GBM",
  "authors": [
    "A. Camero-Arranz",
    "M. H. Finger",
    "N. R. Ikhsanov",
    "C. A. Wilson-Hodge",
    "E. Beklen"
  ],
  "comment": "2009 Fermi Symposium, eConf Proceedings C091122",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Recent X-ray observations by Fermi/GBM discovered a new torque reversal of 4U 1626-67 after 18 years of steady spinning down. Using Swift/BAT observations we were able to center this new torque reversal on Feb 4 2008, lasting approximately 150 days. From 2004 up to the end of 2007, the spin-down rate averaged at a mean rate of ~dnu/dt=-4.8e-13 Hz s-1 until the torque reversal reported here. Since then it has been following a steady spin-up at a mean rate of ~dnu/dt= 4e-13 Hz s-1. The properties of this torque reversal, as well as the lack of correlation between the X-ray flux and the torque applied to the neutron star before this transition, challenges our understanding of the physical mechanisms operating in this system.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-12-18T21:26:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "torque reversal",
      "accreting x-ray pulsar 4u",
      "mean rate",
      "swift/bat observations",
      "x-ray observations"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 840750,
      "adsabs": "2009arXiv0912.3809C"
    }
  }
}