{
  "id": "1804.11344",
  "version": "v1",
  "published": "2018-04-30T17:46:40.000Z",
  "updated": "2018-04-30T17:46:40.000Z",
  "title": "The Density-Magnetic Field Relation in the Atomic ISM",
  "authors": [
    "Adriana Gazol",
    "Marco Villagran"
  ],
  "comment": "Accepted for publication in MNRAS, 10 pages, 11 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present numerical experiments aimed to study the correlation between the magnetic field strength, $B$, and the density, $n$, in the cold atomic interstellar medium (CNM). We analyze 24 magneto-hydrodynamic models with different initial magnetic field intensities ($B_0=$0.4, 2.1, 4.2, and 8.3 $\\mu$G) and/or mean densities (2, 3, and 4 cm$^{-3}$), in the presence of driven and decaying turbulence, with and without self-gravity, in a cubic computational domain with 100 pc by side. Our main findings are: i) For forced simulations, which reproduce the main observed physical conditions of the CNM in the Solar neighborhood, a positive correlation between $B$ and $n$ develops for all the $B_0$ values. ii) The density at which this correlation becomes significant ($\\lesssim 30$ cm$^{-3}$) depends on $B_0$ but is not sensitive to the presence of self-gravity. iii) The effect of self-gravity, when noticeable, consists of producing a shallower correlation at high densities, suggesting that, in the studied regime, self-gravity induces motions along the field lines. iv) Self-gravitating decaying models where the CNM is subsonic and sub-Alfv\\'enic with $\\beta\\lesssim 1$ develop a high density positive correlation whose slopes are consistent with a constant $\\beta(n)$. v) Decaying models where the low density CNM is subsonic and sub-Alfv\\'enic with $\\beta>1$ show a negative correlation at intermediate densities, followed by a high density positive correlation.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-04-30T17:46:40.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "density-magnetic field relation",
      "atomic ism",
      "high density positive correlation",
      "initial magnetic field intensities",
      "cold atomic interstellar medium"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}