--- DOAJ_listed: '1' OA_place: publisher OA_type: gold PlanS_conform: '1' _id: '23092' abstract: - lang: eng text: We present the number density of massive (log(M*/Mo)> 10.3) quiescent galaxies at 2 < z < 5 using JWST NIRSpec PRISM spectra. This work relies on spectra from RUBIES, which provides excellent data quality and an unparalleled, well-defined targeting strategy to robustly infer physical properties and number densities. We identify quiescent galaxy candidates within RUBIES through principal component analysis and construct a final sample using star formation histories derived from spectrophotometric fitting of the NIRSpec PRISM spectra and NIRCam photometry. By inverting the RUBIES selection function, we correct for survey incompleteness and calculate the number density of massive quiescent galaxies at these redshifts, providing the most complete spectroscopic estimates prior to cosmic noon to date. We find that early massive quiescent galaxies are surprisingly common (≳10−5 Mpc−3 by 4 < z < 5), which is consistent with previous studies based on JWST photometry alone and/or in smaller survey areas. We compare our number densities with predictions from six state-of-the-art cosmological galaxy formation simulations. At z > 3, most simulations fail to produce enough massive quiescent galaxies, suggesting the treatment of feedback and/or the channels for early efficient formation are incomplete in most galaxy evolution models. acknowledgement: "We thank Alan Pearl for his contribution to estimating the cosmic variance contribution to the number density uncertainties in this work. We thank Hans-Walter Rix for the valuable discussion on the selection function and correcting the spectroscopic incompleteness of massive quiescent galaxies in RUBIES.\r\n\r\nSome of the data products presented herein were retrieved from the Dawn JWST Archive (DJA). DJA is an initiative of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140.\r\n\r\nThe Cosmic Dawn Center is funded by the Danish National Research Foundation (DNRF) under grant #140.\r\n\r\nSupport for this work was provided by The Brinson Foundation through a Brinson Prize Fellowship grant.\r\n\r\nR.B. gratefully acknowledges support from the Research Corporation for Scientific Advancement (RCSA) Cottrell Scholar Award ID No: 27587.\r\n\r\nThe work of C.C.W. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.\r\n\r\nT.B.M. was supported by a CIERA Postdoctoral Fellowship.\r\n\r\nThis work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program numbers 1180, 1181, 1210, 1211, 1213, 1214, 1215, 1286, 1345, 1433, 1747, 2028, 2073, 2198, 2282, 2561, 2565, 2750, 2756, 2767, 3073, 3215, 4233, 4446, 4557, 6368, 6541, and 6585. The specific observations analyzed can be accessed via DOI: 10.17909/sjsj-8p46.\r\n\r\nSupport for program No. 4233 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127.\r\n\r\nThe authors acknowledge the CEERS and PRIMER teams for developing their observing program with a zero-exclusive access period.\r\n\r\nFacility: JWST - James Webb Space Telescope.\r\n\r\nSoftware: Astropy (Astropy Collaboration et al. 2013, 2018, 2022), Scipy (P. Virtanen et al. 2020), Photutils (L. Bradley 2023), SpectRes (A. C. Carnall 2017), Scikit-learn (F. Pedregosa et al. 2011), Prospector (B. Johnson & J. Leja 2017; J. Leja et al. 2017; B. Johnson et al. 2021)." article_number: '252' article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Yunchong full_name: Zhang, Yunchong last_name: Zhang - first_name: Anna full_name: De Graaff, Anna last_name: De Graaff - first_name: David J. full_name: Setton, David J. last_name: Setton - first_name: Sedona H. full_name: Price, Sedona H. last_name: Price - first_name: Rachel full_name: Bezanson, Rachel last_name: Bezanson - first_name: Claudia full_name: Del P. Lagos, Claudia last_name: Del P. Lagos - first_name: Sam E. full_name: Cutler, Sam E. last_name: Cutler - first_name: Ian full_name: Mcconachie, Ian last_name: Mcconachie - first_name: Nikko J. full_name: Cleri, Nikko J. last_name: Cleri - first_name: Olivia R. full_name: Cooper, Olivia R. last_name: Cooper - first_name: Rashmi full_name: Gottumukkala, Rashmi last_name: Gottumukkala - first_name: Jenny E. full_name: Greene, Jenny E. last_name: Greene - first_name: Michaela full_name: Hirschmann, Michaela last_name: Hirschmann - first_name: Gourav full_name: Khullar, Gourav last_name: Khullar - first_name: Ivo full_name: Labbe, Ivo last_name: Labbe - first_name: Joel full_name: Leja, Joel last_name: Leja - first_name: Michael V. full_name: Maseda, Michael V. last_name: Maseda - first_name: Jorryt J full_name: Matthee, Jorryt J id: 7439a258-f3c0-11ec-9501-9df22fe06720 last_name: Matthee orcid: 0000-0003-2871-127X - first_name: Tim B. full_name: Miller, Tim B. last_name: Miller - first_name: Themiya full_name: Nanayakkara, Themiya last_name: Nanayakkara - first_name: Katherine A. full_name: Suess, Katherine A. last_name: Suess - first_name: Bingjie full_name: Wang, Bingjie last_name: Wang - first_name: Katherine E. full_name: Whitaker, Katherine E. last_name: Whitaker - first_name: Christina C. full_name: Williams, Christina C. last_name: Williams citation: ama: Zhang Y, De Graaff A, Setton DJ, et al. RUBIES spectroscopically confirms the high number density of quiescent galaxies from2<z<5. The Astrophysical Journal. 2026;997(2). doi:10.3847/1538-4357/ae24e1 apa: Zhang, Y., De Graaff, A., Setton, D. J., Price, S. H., Bezanson, R., Del P. Lagos, C., … Williams, C. C. (2026). RUBIES spectroscopically confirms the high number density of quiescent galaxies from2<z<5. The Astrophysical Journal. IOP Publishing. https://doi.org/10.3847/1538-4357/ae24e1 chicago: Zhang, Yunchong, Anna De Graaff, David J. Setton, Sedona H. Price, Rachel Bezanson, Claudia Del P. Lagos, Sam E. Cutler, et al. “RUBIES Spectroscopically Confirms the High Number Density of Quiescent Galaxies From2<z<5.” The Astrophysical Journal. IOP Publishing, 2026. https://doi.org/10.3847/1538-4357/ae24e1. ieee: Y. Zhang et al., “RUBIES spectroscopically confirms the high number density of quiescent galaxies from2<z<5,” The Astrophysical Journal, vol. 997, no. 2. IOP Publishing, 2026. ista: Zhang Y, De Graaff A, Setton DJ, Price SH, Bezanson R, Del P. Lagos C, Cutler SE, Mcconachie I, Cleri NJ, Cooper OR, Gottumukkala R, Greene JE, Hirschmann M, Khullar G, Labbe I, Leja J, Maseda MV, Matthee JJ, Miller TB, Nanayakkara T, Suess KA, Wang B, Whitaker KE, Williams CC. 2026. RUBIES spectroscopically confirms the high number density of quiescent galaxies from2<z<5. The Astrophysical Journal. 997(2), 252. mla: Zhang, Yunchong, et al. “RUBIES Spectroscopically Confirms the High Number Density of Quiescent Galaxies From2<z<5.” The Astrophysical Journal, vol. 997, no. 2, 252, IOP Publishing, 2026, doi:10.3847/1538-4357/ae24e1. short: Y. Zhang, A. De Graaff, D.J. Setton, S.H. Price, R. Bezanson, C. Del P. Lagos, S.E. Cutler, I. Mcconachie, N.J. Cleri, O.R. Cooper, R. Gottumukkala, J.E. Greene, M. Hirschmann, G. Khullar, I. Labbe, J. Leja, M.V. Maseda, J.J. Matthee, T.B. Miller, T. Nanayakkara, K.A. Suess, B. Wang, K.E. Whitaker, C.C. Williams, The Astrophysical Journal 997 (2026). date_created: 2026-10-11T22:02:05Z date_published: 2026-02-01T00:00:00Z date_updated: 2026-10-12T11:55:05Z day: '01' ddc: - '520' department: - _id: JoMa doi: 10.3847/1538-4357/ae24e1 external_id: arxiv: - '2508.08577' file: - access_level: open_access checksum: 547c63f9265be5d41efdc555a25423cc content_type: application/pdf creator: dernst date_created: 2026-10-12T11:51:24Z date_updated: 2026-10-12T11:51:24Z file_id: '23110' file_name: 2026_AstrophysicalJour_Zhang.pdf file_size: 5995619 relation: main_file success: 1 file_date_updated: 2026-10-12T11:51:24Z fulldoi: https://doi.org/10.3847/1538-4357/ae24e1 has_accepted_license: '1' intvolume: ' 997' issue: '2' language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '02' oa: 1 oa_version: Published Version publication: The Astrophysical Journal publication_identifier: eissn: - 1538-4357 issn: - 0004-637X publication_status: published publisher: IOP Publishing quality_controlled: '1' scopus_import: '1' status: public title: RUBIES spectroscopically confirms the high number density of quiescent galaxies from2