{
  "id": "1505.07456",
  "version": "v1",
  "published": "2015-05-27T20:00:28.000Z",
  "updated": "2015-05-27T20:00:28.000Z",
  "title": "The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar",
  "authors": [
    "Giacomo Monari",
    "Benoit Famaey",
    "Arnaud Siebert"
  ],
  "comment": "9 pages, 6 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Evidence for non-zero mean stellar velocities in the direction perpendicular to the Galactic plane has been accumulating from various recent large spectroscopic surveys. Previous analytical and numerical work has shown that a \"breathing mode\" of the Galactic disc, similar to what is observed in the Solar vicinity, can be the natural consequence of a non-axisymmetric internal perturbation of the disc. Here we provide a general analytical framework, in the context of perturbation theory, allowing us to compute the vertical bulk motions generated by a single internal perturber (bar or spiral pattern). In the case of the Galactic bar, we show that these analytically predicted bulk motions are well in line with the outcome of a numerical simulation. The mean vertical motions induced by the Milky Way bar are small (mean velocity of less than 1 km/sec) and cannot be responsible alone for the observed breathing mode, but they are existing. Our analytical treatment is valid close to the plane for all the non-axisymmetric perturbations of the disc that can be described by small-amplitude Fourier modes. Further work should study how the coupling of multiple internal perturbers and external perturbers is affecting the present analytical results.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-05-27T20:00:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic bar",
      "perturbation theory",
      "disc non-axisymmetries",
      "vertical effects",
      "non-zero mean stellar velocities"
    ],
    "publication": {
      "doi": "10.1093/mnras/stv1206"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1373574
    }
  }
}