{
  "id": "1512.08145",
  "version": "v1",
  "published": "2015-12-26T20:52:28.000Z",
  "updated": "2015-12-26T20:52:28.000Z",
  "title": "An Empirical Relation Between The Large-Scale Magnetic Field And The Dynamical Mass In Galaxies",
  "authors": [
    "F. S. Tabatabaei",
    "T. P. K. Martinsson",
    "J. H. Knapen",
    "J. E. Beckman",
    "B. Koribalski",
    "B. G. Elmegreen"
  ],
  "comment": "22 pages, 4 figures, submitted to Astrophysical Journal Letters",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The origin and evolution of cosmic magnetic fields as well as the influence of the magnetic fields on the evolution of galaxies are unknown. Though not without challenges, the dynamo theory can explain the large-scale coherent magnetic fields which govern galaxies, but observational evidence for the theory is so far very scarce. Putting together the available data of non-interacting, non-cluster galaxies with known large-scale magnetic fields, we find a tight correlation between the integrated polarized flux density and the rotation speed, v(rot), of galaxies. This leads to an almost linear correlation between the large-scale magnetic field B and v(rot), assuming that the number of cosmic ray electrons is proportional to the star formation rate. This correlation cannot be attributed to an active linear dynamo processes, as no correlation holds with shear or angular speed. It indicates instead a coupling between the large-scale magnetic field and the dynamical mass of the galaxies, B~M(dyn)^{0.2-0.3}. Hence, faster rotating and/or more massive galaxies have stronger large-scale magnetic fields. The observed B-v(rot) correlation shows that the anisotropic turbulent magnetic field dominates B in fast rotating galaxies as the turbulent magnetic field, coupled with gas, is enhanced and ordered due to the strong gas compression and/or shear in these systems. This study supports a stationary condition and no further evolution of the large-scale magnetic field as long as the dynamical mass of galaxies is constant.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-12-26T20:52:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "dynamical mass",
      "empirical relation",
      "anisotropic turbulent magnetic field dominates",
      "correlation",
      "large-scale coherent magnetic fields"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}