{ "abstract": "At low redshift, massive quiescent galaxies (MQGs) are most frequently found in massive, rich galaxy clusters, but at high redshift the trend is less clear. Here, we present spectroscopic evidence of the effects of environment on the formation and assembly of high-redshift MQGs. We identify 26 (9) log ( M * / M ⊙ ) ≥ 10.5 ( 10.0 ≤ log ( M * / M ⊙ ) < 10.5 ) spectroscopically confirmed quiescent galaxies in the UDS and EGS fields at 3 < z < 5 with NIRSpec spectroscopy from the Red Unknowns: Bright Infrared Extragalactic Spectroscopic (RUBIES) survey and other public JWST programs. We measure the density contrast in these fields by applying a Monte Carlo Voronoi tessellation density-mapping technique to photometric and spectroscopic redshifts of m F444W < 27.5 sources. We robustly detect 19 massive overdense peaks with log ( M Peak / M ⊙ ) ≥ 13 and seven extended massive protoclusters ( log ( M Struct / M ⊙ ) ≥ 13.85 ). We observe that MQGs are preferentially found in these massive peaks and within these massive structures: ≈50% of MQGs are found in massive peaks, compared to ≈25% of massive star-forming galaxies (MSFGs), and quiescent fractions are higher in these regions than in the coeval field. We show that when all stellar mass is assumed to form in situ, the inferred masses of MQG progenitors are significantly higher than those of high- z massive galaxies in observations or simulations. Accounting for ex situ star formation and scaling merger rates by the local galaxy overdensity significantly lessens this tension, which indicates that ex situ star formation plays a key role in MQG mass assembly in overdense environments.", "abstract_shown": true, "affiliations": [ "University of Wisconsin–Madison", "Observatories of the Carnegie Institution for Science,", "Max-Planck-Institut für Astronomie", "The Pennsylvania State University", "University of Pittsburgh", "Princeton University", "The William H. Miller III Department of Physics and Astronomy", "Leiden University", "Cosmic Dawn Center (DAWN)", "University of Copenhagen", "University of Colorado", "Swinburne University of Technology", "Institute of Physics", "University of Washington", "Institute of Science and Technology Austria (ISTA)", "Northwestern University", "MIT Kavli Institute for Astrophysics and Space Research", "Institute for Astronomy, University of Hawai‘i,", "University of Geneva", "Space Telescope Science Institute", "University of Massachusetts", "NSF National Optical-Infrared Astronomy Research Laboratory" ], "article_type": null, "arxiv": null, "author_total": 30, "authors": [ { "affs": [ 0, 1 ], "name": "Ian McConachie", "orcid": "0000-0002-2446-8770" }, { "affs": [ 2 ], "name": "Anna de Graaff", "orcid": "0000-0002-2380-9801" }, { "affs": [ 0 ], "name": "Michael V. Maseda", "orcid": "0000-0003-0695-4414" }, { "affs": [ 3 ], "name": "Joel Leja", "orcid": "0000-0001-6755-1315" }, { "affs": [ 4 ], "name": "Yunchong Zhang", "orcid": "0000-0001-6454-1699" }, { "affs": [ 5, 6 ], "name": "David J. Setton", "orcid": "0000-0003-4075-7393" }, { "affs": [ 4 ], "name": "Rachel Bezanson", "orcid": "0000-0001-5063-8254" }, { "affs": [ 7 ], "name": "Leindert A. Boogaard", "orcid": "0000-0002-3952-8588" }, { "affs": [ 8, 9 ], "name": "Gabriel Brammer", "orcid": "0000-0003-2680-005X" }, { "affs": [ 3 ], "name": "Nikko J. Cleri", "orcid": "0000-0001-7151-009X" }, { "affs": [ 10 ], "name": "Olivia R. Cooper", "orcid": "0000-0003-3881-1397" }, { "affs": [ 11 ], "name": "Karl Glazebrook", "orcid": "0000-0002-3254-9044" }, { "affs": [ 8, 9 ], "name": "Rashmi Gottumukkala", "orcid": "0000-0003-0205-9826" }, { "affs": [ 5 ], "name": "Jenny E. Greene", "orcid": "0000-0002-5612-3427" }, { "affs": [ 5 ], "name": "Andy D. Goulding", "orcid": "0000-0003-4700-663X" }, { "affs": [ 12 ], "name": "Michaela Hirschmann", "orcid": "0000-0002-3301-3321" }, { "affs": [ 13 ], "name": "Gourav Khullar", "orcid": "0000-0002-3475-7648" }, { "affs": [ 11 ], "name": "Ivo Labbe", "orcid": "0000-0002-2057-5376" }, { "affs": [ 0 ], "name": "Zach Lewis" }, { "affs": [ 14 ], "name": "Jorryt Matthee", "orcid": "0000-0003-2871-127X" }, { "affs": [ 15 ], "name": "Tim B. Miller", "orcid": "0000-0001-8367-6265" }, { "affs": [ 16, 17 ], "name": "Rohan P. Naidu", "orcid": "0000-0003-3997-5705" }, { "affs": [ 11 ], "name": "Themiya Nanayakkara", "orcid": "0000-0003-2804-0648" }, { "affs": [ 10 ], "name": "Erica J. Nelson", "orcid": "0000-0002-7524-374X" }, { "affs": [ 8, 9, 18 ], "name": "Pascal A. Oesch", "orcid": "0000-0001-5851-6649" }, { "affs": [ 4, 19 ], "name": "Sedona H. Price", "orcid": "0000-0002-0108-4176" }, { "affs": [ 10 ], "name": "Katherine A. Suess", "orcid": "0000-0002-1714-1905" }, { "affs": [ 5 ], "name": "Bingjie Wang", "orcid": "0000-0001-9269-5046" }, { "affs": [ 8, 20 ], "name": "Katherine E. Whitaker", "orcid": "0000-0001-7160-3632" }, { "affs": [ 21 ], "name": "Christina C. Williams", "orcid": "0000-0003-2919-7495" } ], "bibtex": "https://research.draconitic.com/paper/6y3ht5ark67pq.bib", "cited_by": 0, "doi": "10.3847/1538-4357/aea6b5", "fulltext_url": null, "id": "6y3ht5ark67pq", "issns": [ "1538-4357", "0004-637X" ], "landing_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea6b5", "language": null, "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "feed-journal", "astronomy/general" ] ], "openalex": null, "pdf_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea6b5/pdf", "pmcid": null, "pmid": null, "published": "2026-11-02", "publisher": "American Astronomical Society", "ris": "https://research.draconitic.com/paper/6y3ht5ark67pq.ris", "sources": [ { "first_seen": "2026-11-03T00:20:19Z", "native_id": "10.3847/1538-4357/aea6b5", "source": "feed-iop", "url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea6b5" }, { "first_seen": "2026-11-03T00:21:56Z", "native_id": "10.3847/1538-4357/aea6b5", "source": "crossref", "url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea6b5" } ], "subjects": [ { "field": "astronomy", "origin": "journal-openalex:3103|Stellar, planetary, and galactic studies", "subfield": "stellar" } ], "title": "Where Galaxies Go to Die: The Environments of Massive Quiescent Galaxies at 3 < z < 5", "title_text": "Where Galaxies Go to Die: The Environments of Massive Quiescent Galaxies at 3 < z < 5", "type": "peer-reviewed", "updated_at": "2026-11-04T00:22:41Z", "url": "https://research.draconitic.com/paper/6y3ht5ark67pq", "venue": "The Astrophysical Journal", "versions": [] }