{
  "id": "0911.4004",
  "version": "v1",
  "published": "2009-11-20T10:44:33.000Z",
  "updated": "2009-11-20T10:44:33.000Z",
  "title": "Cosmic Ray Acceleration in Active Galactic Nuclei - On Centaurus A as a possible UHECR Source",
  "authors": [
    "Frank M. Rieger"
  ],
  "comment": "8 pages, one figure; based on invited talk at the JEM-EUSO Workshop, Torino/Italy, December 2008. To appear in Proceedings of the JEM-EUSO Workshop, under publication by UAP Tokyo, Japan",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We discuss a representative selection of particle acceleration mechanisms believed to be operating in Active Galactic Nuclei. Starting from direct electrostatic field acceleration in the vicinity of the black hole up to Fermi-type particle acceleration in the jet and beyond, possible efficiency constraints on the energization of ultra-high energy cosmic rays (UHECR) are evaluated. When paradigmatically applied to Cen A, the following results are obtained: (i) Proton acceleration to energies of $E_c = 5\\times 10^{19}$ eV and beyond remains challenging and most likely requires the operation of an additional mechanism capable of boosting energetic seed protons up by a factor of $\\sim$ten. It is argued that shear acceleration along the large-scale jet in Cen A could be a promising candidate for this. (ii) Heavier elements, like iron nuclei, are more easily accelerated (by, e.g., shocks or direct electrostatic fields) and may not need additional boosting to reach $E \\geq E_c$; (iii) If Cen A indeed proves to be an UHECR source, the cosmic ray composition might thus be expected to become heavier above energies of a few times $10^{19}$ eV.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-11-20T10:44:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "active galactic nuclei",
      "cosmic ray acceleration",
      "uhecr source",
      "direct electrostatic field acceleration",
      "ultra-high energy cosmic rays"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 837441,
      "adsabs": "2009arXiv0911.4004R"
    }
  }
}