{
  "abstract": "With microarcsecond precision, \\textit{Gaia} has made the astrometric discovery of substellar companions feasible. However, follow-up observations are needed to check on orbital solutions and rule out astrophysical false positives. We validate and characterise a sample of 20 \\textit{Gaia} Data Release 3 (DR3) astrometric candidates for substellar companions, with the dual goal of identifying false positives and deriving robust physical parameters for genuine companions. We performed high-resolution spectroscopy using FIES, NIRPS, and NEID at the Nordic Optical Telescope, the ESO 3.6m telescope, and the WIYN Telescope, respectively. Double-lined spectroscopic binaries were identified as false positives, and surviving systems were characterised through joint \\textit{Gaia} astrometry and radial velocity modelling. Thirteen of the candidates proved to be near-twin binary stars for which the astrometric motion of the center of light is small enough to mimic that of a single star in response to a substellar companion. We confirm that six companions are brown dwarfs with masses in the range ${\\sim}26$--$68\\,M_\\mathrm{Jup}$, two of them for the first time. In contrast to earlier studies of lower-mass \\textit{Gaia} candidates, we find that the astrometric orbital solutions are generally reliable to within the stated uncertainties.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.08590",
  "author_total": 10,
  "authors": [
    {
      "name": "Marcus L. Marcussen"
    },
    {
      "name": "Simon H. Albrecht"
    },
    {
      "name": "Kamil K. Kalinowski"
    },
    {
      "name": "Joshua N. Winn"
    },
    {
      "name": "Guðmundur Stefánsson"
    },
    {
      "name": "Jens Reersted Larsen"
    },
    {
      "name": "Julie Gadeberg"
    },
    {
      "name": "Evan Fitzmaurice"
    },
    {
      "name": "Kevin Schlaufman"
    },
    {
      "name": "Suvrath Mahadevan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9sabx2s1ptpsq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.08590",
  "fulltext_url": null,
  "id": "9sabx2s1ptpsq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.08590",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.EP"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7212023655",
  "pdf_url": "https://arxiv.org/pdf/2609.08590",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9sabx2s1ptpsq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:52Z",
      "native_id": "2609.08590",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.08590"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Radial velocity follow-up of \\textit{Gaia} astrometric substellar companions: six confirmed brown dwarfs and 13 impostor binaries",
  "title_text": "Radial velocity follow-up of \\textit{Gaia} astrometric substellar companions: six confirmed brown dwarfs and 13 impostor binaries",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:52Z",
  "url": "https://research.draconitic.com/paper/9sabx2s1ptpsq",
  "venue": "arXiv",
  "versions": []
}