{
  "id": "2112.00026",
  "version": "v2",
  "published": "2021-11-30T19:00:03.000Z",
  "updated": "2022-09-20T05:27:21.000Z",
  "title": "The phenomenology of the external field effect in cold dark matter models",
  "authors": [
    "Aseem Paranjape",
    "Ravi K. Sheth"
  ],
  "comment": "11 pages, 6 figures; v2: minor changes and added discussion, accepted in MNRAS",
  "categories": [
    "astro-ph.CO",
    "astro-ph.GA"
  ],
  "abstract": "In general relativity (GR), the internal dynamics of a self-gravitating system under free-fall in an external gravitational field should not depend on the external field strength. Recent work has claimed a statistical detection of an `external field effect' (EFE) using galaxy rotation curve data. We show that large uncertainties in rotation curve analyses and inaccuracies in published simulation-based external field estimates compromise the significance of the claimed EFE detection. We further show analytically that a qualitatively similar statistical signal is, in fact, expected in a $\\Lambda$-cold dark matter ($\\Lambda$CDM) universe without any violation of the strong equivalence principle. Rather, such a signal arises simply because of the inherent correlations between galaxy clustering strength and intrinsic galaxy properties. We explicitly demonstrate the effect in a baryonified mock catalog of a $\\Lambda$CDM universe. Although the detection of an EFE-like signal is not, by itself, evidence for physics beyond GR, our work shows that the $\\textit{sign}$ of the EFE-like correlation between the external field strength and the shape of the radial acceleration relation can be used to probe new physics: e.g., in MOND, the predicted sign is opposite to that in our $\\Lambda$CDM mocks.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2022-09-20T05:27:21.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "cold dark matter models",
      "external field effect",
      "external field estimates compromise",
      "simulation-based external field estimates",
      "external field strength"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}