{
  "abstract": "The Little Red Dots (LRDs) are compact, red sources, abundant at $4 \\lesssim z \\lesssim 9$ and likely powered by massive black holes. Photometric studies have found blue companions around them, but none has yet been confirmed spectroscopically. This Letter presents the only two LRD-companion pairs with spectroscopy of both members in the literature: \"Waltz\" at $z = 3.9$ and \"Tango\" at $z = 5.5$, with projected separations of $3.6$ and $2.5$ kpc. Both companions lie at the redshift of their LRD, within $132 \\, \\rm km \\, s^{-1}$ and $57 \\, \\rm km \\, s^{-1}$, and are physically identical, but $524$ Myr apart: starbursts $\\lesssim 50$ Myr old, metal-poor ($0.2 \\, \\rm Z_\\odot$), dust-free, dynamically cold, and as bright as the LRDs themselves in the rest-frame UV. The LRD in Waltz hosts a $\\approx 3 \\times 10^{6} \\, \\rm M_\\odot$ black hole accreting at half the Eddington rate, a factor of a few above the birth mass of a direct collapse black hole, and is embedded in gas as metal-poor as its companion. Orbital modeling shows that Tango is bound in $81\\%$ of the allowed orbits and that Waltz is bound if its host halo exceeds $5 \\times 10^{10} \\, \\rm M_\\odot$. Both blue companions then merge with their respective LRD within a few hundred Myr. We conclude that we are observing what heavy seeding requires: a young black hole beside the metal-poor starburst that the synchronized-pair scenario predicts, in the last steps of a cosmic dance that ends in a merger, and in a galaxy seeded by its black hole.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18968",
  "author_total": 2,
  "authors": [
    {
      "name": "Fabio Pacucci"
    },
    {
      "name": "Pierluigi Rinaldi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/916k86v63skxk.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18968",
  "fulltext_url": null,
  "id": "916k86v63skxk",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18968",
  "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.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7222331131",
  "pdf_url": "https://arxiv.org/pdf/2610.18968",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/916k86v63skxk.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.18968",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18968"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "The Dance of the Little Red Dots: Spectroscopy of Two Blue Companions at z = 3.9 and 5.5 Reveals Young, Metal-Poor Starbursts Merging with Their LRDs within a Few Hundred Myr",
  "title_text": "The Dance of the Little Red Dots: Spectroscopy of Two Blue Companions at z = 3.9 and 5.5 Reveals Young, Metal-Poor Starbursts Merging with Their LRDs within a Few Hundred Myr",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/916k86v63skxk",
  "venue": "arXiv",
  "versions": []
}