{
  "id": "1905.09619",
  "version": "v1",
  "published": "2019-05-23T12:38:18.000Z",
  "updated": "2019-05-23T12:38:18.000Z",
  "title": "Testing Modified Gravity with Wide Binaries in GAIA DR2",
  "authors": [
    "Charalambos Pittordis",
    "Will Sutherland"
  ],
  "comment": "Latex, 14 pages, 11 figures. Submitted to MNRAS, 21 May 2019",
  "categories": [
    "astro-ph.CO",
    "astro-ph.GA",
    "gr-qc"
  ],
  "abstract": "Several recent studies have shown that very wide binary stars can potentially provide an interesting test for modified-gravity theories which attempt to emulate dark matter; these systems should be almost Newtonian according to standard dark-matter theories, while the predictions for MOND-like theories are distinctly different, if the various observational issues can be overcome. Here we explore an observational application of the test from the recent GAIA DR2 data release: we select a large sample of $\\sim 24,000$ candidate wide binary stars with distance $< 200$ parsec and magnitudes $G < 16$ from GAIA DR2, and estimated component masses using a main-sequence mass-luminosity relation. We then compare the frequency distribution of pairwise relative projected velocity (relative to circular-orbit value) as a function of projected separation; these distributions show a clear peak at a value close to Newtonian expectations, along with a long `tail' which extends to much larger velocity ratios; the `tail' is considerably more numerous than in control samples constructed from DR2 with randomised positions, so its origin is unclear. Comparing the velocity histograms with simulated data, we conclude that MOND-like theories without an external field effect are strongly inconsistent with the observed data since they predict a peak-shift in clear disagreement with the data; testing MOND-like theories with an external field effect is not decisive at present, but has good prospects to become decisive in future with improved modelling or understanding of the high-velocity tail, and additional spectroscopic data.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-05-23T12:38:18.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gaia dr2",
      "testing modified gravity",
      "external field effect",
      "mond-like theories",
      "candidate wide binary stars"
    ],
    "note": {
      "typesetting": "LaTeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}