{
  "abstract": "Recent JWST observations have revealed an overabundance of quiescent galaxies at high redshift. Photometric methods, such as photometry-derived sSFRs, $UVJ$ colors, and synthetic $ugi_s$ colors, are commonly used to identify quiescent galaxies, but their completeness and purity remain poorly constrained. Here we present a spectroscopically selected sample of 19 quiescent galaxies at $2 \\leq z \\leq 4$ from the CANDELS-Area Prism Epoch of Reionization Survey (CAPERS). They are selected with $M_\\ast > 10^{9.5} M_\\odot$ and a specific star formation rate below 20% of the inverse cosmic age. These galaxies formed 50% of their stellar mass at $z \\sim 3.0$--4.6 and quenched rapidly on timescales of $\\sim0.1$--0.2 Gyr. These quenching timescales are comparable to those of other high-redshift QGs but shorter than those at lower redshift. Using the spectroscopic sample as a benchmark, we assess commonly adopted photometric QG selection methods. We find completeness of 63--89% and purities of only 40--63%, with strong emission-line galaxies constituting the dominant source of contamination. Applying completeness and purity corrections calibrated from the spectroscopic sample, we measure the number density of quiescent galaxies at $2 \\leq z \\leq 5$. The resulting number densities exceed the predictions of most current galaxy-formation simulations at $2<z<4$, with the largest discrepancy at $M_\\ast \\geq 10^{10.5} M_\\odot$. This discrepancy suggests that current cosmological models may not assemble and quench massive galaxies sufficiently early or efficiently.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.20931",
  "author_total": 31,
  "authors": [
    {
      "name": "Lu Shen"
    },
    {
      "name": "Weida Hu"
    },
    {
      "name": "Casey Papovich"
    },
    {
      "name": "Justin Cole"
    },
    {
      "name": "Mark Dickinson"
    },
    {
      "name": "Pablo Arrabal Haro"
    },
    {
      "name": "Anthony J. Taylor"
    },
    {
      "name": "Adam C. Carnall"
    },
    {
      "name": "Ángel Chandro-Gómez"
    },
    {
      "name": "Yingjie Cheng"
    },
    {
      "name": "Nikko J. Cleri"
    },
    {
      "name": "James S. Dunlop"
    },
    {
      "name": "Carter Flayhart"
    },
    {
      "name": "Steven L. Finkelstein"
    },
    {
      "name": "Mauro Giavalisco"
    },
    {
      "name": "Michaela Hirschmann"
    },
    {
      "name": "Eric F. Jiménez-Andrade"
    },
    {
      "name": "Jeyhan S. Kartaltepe"
    },
    {
      "name": "Claudia D. P. Lagos"
    },
    {
      "name": "Ho-Hin Leung"
    },
    {
      "name": "Arianna S. Long"
    },
    {
      "name": "Ray A. Lucas"
    },
    {
      "name": "Eric J. Murphy"
    },
    {
      "name": "Lorenzo Napolitano"
    },
    {
      "name": "Pablo G. Pérez-González"
    },
    {
      "name": "Raymond C. Simons"
    },
    {
      "name": "Struan D Stevenson"
    },
    {
      "name": "Elizabeth Taylor"
    },
    {
      "name": "Xin Wang"
    },
    {
      "name": "L. Y. Aaron Yung"
    },
    {
      "name": "Jorge A. Zavala"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2xhfxepmmrztq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.20931",
  "fulltext_url": null,
  "id": "2xhfxepmmrztq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.20931",
  "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": "W7213948909",
  "pdf_url": "https://arxiv.org/pdf/2609.20931",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2xhfxepmmrztq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:03Z",
      "native_id": "2609.20931",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.20931"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Quiescent Galaxies at $z > 2$ from CAPERS spectroscopy and their Number densities",
  "title_text": "Quiescent Galaxies at z > 2 from CAPERS spectroscopy and their Number densities",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:03Z",
  "url": "https://research.draconitic.com/paper/2xhfxepmmrztq",
  "venue": "arXiv",
  "versions": []
}