{
  "abstract": "Einstein's General Relativity (GR), which has been precisely tested on galaxy and solar system scales, is still poorly constrained in extremely weak gravitational fields (with dimensionless Newtonian potentials of $Φ\\sim 10^{-8}$). In this Letter, we propose a new method to probe such a weak-field regime of gravity and measure the spatial curvature generated per unit mass. Specifically, binary microlensing events provide a laboratory to measure the parameterized post-Newtonian (PPN) parameter ($γ$), by combining the lensing mass ($M_{\\rm lens}^{\\rm GR}$) inferred from microlensing with the dynamical mass ($M_{\\rm dyn}$) determined from interferometric astrometry. Astrometric tracking of binary lenses was previously hindered by their faintness and minuscule angular separations (typically a few milliarcseconds). This limitation has been alleviated by the deployment of GRAVITY+, which pushes the instrument's sensitivity and astrometric precision to unprecedented heights. Based on astrometric simulations of the binary microlensing event ASASSN-22av, we directly estimate $γ$ at the precision of ~23%. Such test of GR in the extremely weak-field regime can be further improved to much higher precision (~3%), based on more binary microlensing events with precise determination of the dynamical/lens mass.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Astrophys. J. Lett. 1008 (2026) L41",
  "arxiv": "2610.11949",
  "author_total": 6,
  "authors": [
    {
      "name": "Xinyang Jin"
    },
    {
      "name": "Shuo Cao"
    },
    {
      "name": "Xuanni Chen"
    },
    {
      "name": "Yalong Nan"
    },
    {
      "name": "Xuchen Tai"
    },
    {
      "name": "Shuxun Tian"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4g8jv60fmwqcc.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.11949",
  "fulltext_url": null,
  "id": "4g8jv60fmwqcc",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.11949",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "arxiv",
      "gr-qc"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.11949",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4g8jv60fmwqcc.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.11949",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.11949"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Testing General Relativity with Binary Lens Microlensing Events",
  "title_text": "Testing General Relativity with Binary Lens Microlensing Events",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/4g8jv60fmwqcc",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.3847/2041-8213/ae954b",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}