{
  "abstract": "We explore the prevalence of mini-quenched or ``napping'' galaxies selected from spectroscopic and photometric samples in the UNCOVER/MegaScience survey. These galaxies are empirically identified by the presence of moderate Balmer breaks, weak emission lines ($EW(Hα) < 100$A) and relatively blue UV continua. We infer the star formation histories (SFHs) of our sample using flexible non-parametric models with Prospector optimized to capture recent episodes of bursty star formation and quenching, and find that they are uniquely identifiable in the SFR$_{10}$/SFR$_{100}$ parameter space moving towards (temporary) quiescence. We demonstrate that although spectroscopy is best able to identify rapidly declining SFRs, densely sampled medium-band photometry recover these key spectral features and thus robustly identify pure samples of this transient phase -- with imaging alone. We quantify the number density of napping galaxies at $z=4-7$ in the Abell 2744 lensing field, finding 8 spectroscopically confirmed nappers and 60 photometric candidates spanning log$_{10}$(M$_*$/M$_\\odot$) $= 7.5-10$. We verify that the photometry alone can identify a pure sample of nappers, leveraging a smaller high signal-to-noise ratio spectroscopic sample. Consistent with previous studies, we find that nappers are most common at low stellar mass (log$_{10}$(M$_*$/M$_\\odot$) $\\sim9$). We see a hint that the number densities increase from $z\\sim6$ to $z\\sim4$, though our small sample is likely affected by cosmic variance. Our study demonstrates the increasing importance of stochastic star formation as a regulator of low-mass galaxy growth in the several hundred Myr after reionization, and offers a direct observational testbed for the strength and duty cycle of stellar feedback in cosmological simulations.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.30011",
  "author_total": 30,
  "authors": [
    {
      "name": "Gourav Khullar"
    },
    {
      "name": "Rachel Bezanson"
    },
    {
      "name": "Katherine A. Suess"
    },
    {
      "name": "Ikki Mitsuhashi"
    },
    {
      "name": "David J. Setton"
    },
    {
      "name": "Joel Leja"
    },
    {
      "name": "Sedona H. Price"
    },
    {
      "name": "Katherine E. Whitaker"
    },
    {
      "name": "Emilie Burnham"
    },
    {
      "name": "John R. Weaver"
    },
    {
      "name": "Iryna Chemerynska"
    },
    {
      "name": "Lukas J. Furtak"
    },
    {
      "name": "Jenny Greene"
    },
    {
      "name": "Bingjie Wang"
    },
    {
      "name": "Hakim Atek"
    },
    {
      "name": "Gabe Brammer"
    },
    {
      "name": "Olivia R. Cooper"
    },
    {
      "name": "Robert Feldmann"
    },
    {
      "name": "Seiji Fujimoto"
    },
    {
      "name": "Anna de Graaff"
    },
    {
      "name": "Ivo Labbe"
    },
    {
      "name": "Danilo Marchesini"
    },
    {
      "name": "Ian McConachie"
    },
    {
      "name": "Tim B. Miller"
    },
    {
      "name": "Abby Mintz"
    },
    {
      "name": "Themiya Nanayakkara"
    },
    {
      "name": "Pascal Oesch"
    },
    {
      "name": "Richard Pan"
    },
    {
      "name": "Casey Papovich"
    },
    {
      "name": "Yunchong Zhang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bechy1fhatp1y.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.30011",
  "fulltext_url": null,
  "id": "bechy1fhatp1y",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.30011",
  "language": null,
  "licence": "CC-BY-NC-SA-4.0",
  "licence_label": "CC BY-NC-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7204933189",
  "pdf_url": "https://arxiv.org/pdf/2608.30011",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bechy1fhatp1y.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.30011",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.30011"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Caught Napping by JWST UNCOVER+MegaScience: Constraining bursty star formation histories and number densities of mini-quenched galaxies at redshifts 4-7",
  "title_text": "Caught Napping by JWST UNCOVER+MegaScience: Constraining bursty star formation histories and number densities of mini-quenched galaxies at redshifts 4-7",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/bechy1fhatp1y",
  "venue": "arXiv",
  "versions": []
}