{
  "id": "1511.05144",
  "version": "v1",
  "published": "2015-11-16T21:00:01.000Z",
  "updated": "2015-11-16T21:00:01.000Z",
  "title": "Role of Cosmic Rays in the Circumgalactic Medium",
  "authors": [
    "Munier Salem",
    "Greg L. Bryan",
    "Lauren Corlies"
  ],
  "comment": "22 pages, 14 figures, MNRAS in press",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We explore the impact of cosmic rays (CRs) on cosmological adaptive-mesh refinement simulations of a forming 10^12 Msolar halo, focusing on the circumgalactic medium (CGM), and its resulting low-redshift structure and composition. In contrast to a run with star formation and energetic feedback but no CRs, the CR-inclusive runs feature a CGM substantially enriched with CRs and with metals to roughly 0.1 Zsolar, thanks to robust, persistent outflows from the disk. The CR-inclusive CGMs also feature more diffuse gas at lower temperatures, down to 10^4 K, than the non-CR run, with diffuse material often receiving a majority of its pressure support from the CR proton fluid. We compare to recent observations of the CGM of L ~ L* galaxies at low redshift, including UV absorption lines within background quasar spectra. The combination of metal-enriched, CR-driven winds and large swaths of CR pressure-supported, cooler diffuse gas leads to a CGM that provides a better match to data from COS-Halos (for HI, SiIV, CIII and OVI) than the non-CR run. We also compare our models to recent, preliminary observations of diffuse gamma-ray emission in local group halos. For our lower CR-diffusion runs with kappa_CR in the range 0.3 to 1 x 10^28 cm^2/s, the CR enriched CGM produces an inconsistently high level of gamma emission. But the model with a relatively high kappa_CR = 3 x 10^28 cm^2/s provided a gamma-ray luminosity consistent with the extra-galactic gamma-ray background observed by FERMI and roughly consistent with preliminary measures of the emission from M31's CGM.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-11-16T21:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "circumgalactic medium",
      "cosmic rays",
      "non-cr run",
      "diffuse gamma-ray emission",
      "cooler diffuse gas"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}