{
  "id": "1511.07641",
  "version": "v1",
  "published": "2015-11-24T10:47:29.000Z",
  "updated": "2015-11-24T10:47:29.000Z",
  "title": "A recent change in the optical and γ-ray polarization of the Crab nebula and pulsar",
  "authors": [
    "Paul Moran",
    "Gillian Kyne",
    "Christian Gouiffes",
    "3",
    "Philipe Laurent",
    "Gregg Hallinan",
    "Michael Redfern",
    "Andrew Shearer"
  ],
  "comment": "9 pages accepted for publication in MNRAS",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We report on observations of the polarization of optical and {\\gamma}-ray photons from the Crab nebula and pulsar system using the Galway Astronomical Stokes Polarimeter (GASP), the Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) and the International Gamma-Ray Astrophysics Laboratory satellite (Integral). These, when combined with other optical polarization observations, suggest that the polarized optical emission and {\\gamma}-ray polarization changes in a similar manner. A change in the optical polarization angle has been observed by this work, from 109.5 \\pm 0.7\\deg in 2005 to 85.3 \\pm 1.4 \\deg in 2012. On the other hand, the {\\gamma}-ray polarization angle changed from 115 \\pm 11 \\deg in 2003-2007 to 80 \\pm 12 \\deg in 2012-2014. Strong flaring activities have been detected in the Crab nebula over the past few years by the high energy {\\gamma}-ray missions Agile and Fermi, and magnetic reconnection processes have been suggested to explain these observations. The change in the polarized optical and {\\gamma}-ray emission of the Crab nebula/pulsar as observed, for the first time, by GASP and Integral may indicate that reconnection is possibly at work in the Crab nebula. We also report, for the first time, a non-zero measure of the optical circular polarization from the Crab pulsar+knot system.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-11-24T10:47:29.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "crab nebula",
      "international gamma-ray astrophysics laboratory satellite",
      "first time",
      "galway astronomical stokes polarimeter",
      "observations"
    ],
    "publication": {
      "doi": "10.1093/mnras/stv2780"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1406099
    }
  }
}