RUBIES spectroscopically confirms the high number density of quiescent galaxies from2<z<5

Zhang, Yunchong; De Graaff, Anna; Setton, David J.; Price, Sedona H.; Bezanson, Rachel; Del P. Lagos, Claudia; Cutler, Sam E.; Mcconachie, Ian; Cleri, Nikko J.; Cooper, Olivia R.; Gottumukkala, Rashmi; Greene, Jenny E.; Hirschmann, Michaela; Khullar, Gourav; Labbe, Ivo; Leja, Joel; Maseda, Michael V.; Matthee, Jorryt J; Miller, Tim B.; Nanayakkara, Themiya; Suess, Katherine A.; Wang, Bingjie; Whitaker, Katherine E.; Williams, Christina C.

RUBIES spectroscopically confirms the high number density of quiescent galaxies from2

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.

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DOI

10.3847/1538-4357/ae24e1

Journal Article | Published | English

Scopus indexed

Author

Zhang, Yunchong; De Graaff, Anna; Setton, David J.; Price, Sedona H.; Bezanson, Rachel; Del P. Lagos, Claudia; Cutler, Sam E.; Mcconachie, Ian; Cleri, Nikko J.; Cooper, Olivia R.; Gottumukkala, Rashmi; Greene, Jenny E.
All

Department

Matthee Group

Abstract

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.

Publishing Year

2026

Date Published

2026-02-01

Journal Title

The Astrophysical Journal

Publisher

IOP Publishing

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. Some 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. The Cosmic Dawn Center is funded by the Danish National Research Foundation (DNRF) under grant #140. Support for this work was provided by The Brinson Foundation through a Brinson Prize Fellowship grant. R.B. gratefully acknowledges support from the Research Corporation for Scientific Advancement (RCSA) Cottrell Scholar Award ID No: 27587. The 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. T.B.M. was supported by a CIERA Postdoctoral Fellowship. This 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. Support 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. The authors acknowledge the CEERS and PRIMER teams for developing their observing program with a zero-exclusive access period. Facility: JWST - James Webb Space Telescope. Software: 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).

Volume

997

Issue

Article Number

252

ISSN

0004-637X

eISSN

1538-4357

IST-REx-ID

23092

Cite this

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

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

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.

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.

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.

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.

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