{
  "abstract": "The \"Little Red Dots\" (LRDs) uncovered by JWST are typically analyzed as a distinct class of objects; however, whether they are separated from ordinary star-forming galaxies by a genuine boundary has not been tested at the population level. Using a sample of $\\sim3,500$ galaxies at $3 \\lesssim z \\lesssim 8$ with NIRSpec/PRISM spectra from the DAWN JWST Archive, we modeled their rest-frame UV-to-optical continuum emission with power laws and located the sources in the $β_{\\rm{UV}}$-$β_{\\rm{opt}}$ plane. Alongside a dense locus of star-forming galaxies and a diagonal sequence which can be explained by dust reddening and/or quiescence, we identify a vertical sequence extending from the locus of star-forming galaxies into the LRD region. This sequence is smoothly and continuously populated, with no clear boundary between the two populations. Its middle section, $-1 \\lesssim β_{\\rm{opt}} \\lesssim 0$, hosts an intermediate population of $\\sim50$ sources that falls outside the LRD selection boundary and has been largely overlooked; NIRCam imaging shows their rest-frame UV and optical median stacked images lie between point-like LRDs and extended star-forming galaxies. We modeled the vertical sequence as linear mixtures of stacked star-forming spectra and a black hole star (BH*) template derived from \"The Cliff\", one of the most compelling BH* candidates, and we infer black hole-to-stellar mass ratios $η= M_{\\rm{BH}}/M_* \\approx 0.006-0.1$ at the LRD end. We propose $-1 \\lesssim β_{\\rm{opt}} \\lesssim 0$ as a practical selection window for possible transition candidates and argue that LRDs may be the compact, BH*-dominated extreme of a continuous population in which the relative contributions of the host and BH* vary smoothly.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.07025",
  "author_total": 4,
  "authors": [
    {
      "name": "Kristiphong Boonmee"
    },
    {
      "name": "Akio K. Inoue"
    },
    {
      "name": "Masafusa Onoue"
    },
    {
      "name": "Xingyao Cai"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/77g6j0jdwct77.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.07025",
  "fulltext_url": null,
  "id": "77g6j0jdwct77",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.07025",
  "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.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7212020962",
  "pdf_url": "https://arxiv.org/pdf/2609.07025",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/77g6j0jdwct77.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.07025",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.07025"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Between Little Red Dots and Star-Forming Galaxies: A Sequence in the Optical Continuum Slope",
  "title_text": "Between Little Red Dots and Star-Forming Galaxies: A Sequence in the Optical Continuum Slope",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/77g6j0jdwct77",
  "venue": "arXiv",
  "versions": []
}