RUBIES: A complete census of the bright and red distant Universe with JWST/NIRSpec

We present the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES) providing JWST/NIRSpec spectroscopy of red sources selected across ∼150 arcmin 2 from public JWST/NIRCam imaging in the UDS and EGS fields. The novel observing strategy of RUBIES offers a well-quantified selection function. The survey has been optimised to reach high (>70%) spectroscopic completeness for bright and red (F150W−F444W>2) sources that are very rare. To place these rare sources in context, we simultaneously observed a reference sample of the 2< z <7 galaxy population, sampling sources at a rate that is inversely proportional to their number density in the 3D parameter space of F444W magnitude, F150W−F444W colour, and photometric redshift. In total, RUBIES observed ∼3000 targets across 1< z phot <10 with both the PRISM and G395M dispersers and ∼1500 targets at z phot >3 using only the G395M disperser. The RUBIES data reveal a highly diverse population of red sources that span a broad redshift range ( z spec ∼1−9), with photometric redshift scatter and an outlier fraction that are three times higher than for similarly bright sources that are less red. This diversity is not apparent from the photometric spectral energy distributions (SEDs). Only spectroscopy reveals that the SEDs encompass a mixture of galaxies with dust-obscured star formation, extreme line emission, a lack of star formation indicating early quenching, and luminous active galactic nuclei. As a first demonstration of our broader selection function we compared the stellar masses and rest-frame U − V colours of the red sources and our reference sample. We find that the red sources are typically more massive ( M * ∼10 10−11.5 M ⊙ ) across all redshifts. However, we also find that the most massive systems span a wide range in U − V colour. We describe our data reduction procedure and data quality, and we publicly release the reduced RUBIES data and vetted spectroscopic redshifts of the first half of the survey through the DAWN JWST Archive.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-04-15
DOI
https://doi.org/10.1051/0004-6361/202452186
Citations
60
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
71.50

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article

RUBIES: A complete census of the bright and red distant Universe with JWST/NIRSpec

Jorryt Matthee, Rachel Bezanson, Tim B. Miller, Harley Katz et al.
60 citations
Astronomy and Astrophysics
Astronomy and Astrophysical Research
71.50
article

RUBIES: A complete census of the bright and red distant Universe with JWST/NIRSpec

Jorryt Matthee, Rachel Bezanson, Tim B. Miller, Harley Katz, Hans‐Walter Rix, I. McConachie, Rohan P. Naidu, Jenny E. Greene, David J. Setton, Leindert Boogaard, Christina C. Williams, Olivia R. Cooper, Joel Leja, Katherine A. Suess, Nikko J. Cleri, Pascal A. Oesch, Zach Lewis, Gabriel Brammer, Raphael E. Hviding, Rashmi Gottumukkala, Michael V. Maseda, Katherine E. Whitaker, Sedona H. Price, Andrea Weibel, Anna de Graaff, Michaela Hirschmann, Bingjie Wang, Ivo Labbé
article en
60 citations

Abstract

We present the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES) providing JWST/NIRSpec spectroscopy of red sources selected across ∼150 arcmin 2 from public JWST/NIRCam imaging in the UDS and EGS fields. The novel observing strategy of RUBIES offers a well-quantified selection function. The survey has been optimised to reach high (>70%) spectroscopic completeness for bright and red (F150W−F444W>2) sources that are very rare. To place these rare sources in context, we simultaneously observed a reference sample of the 2< z <7 galaxy population, sampling sources at a rate that is inversely proportional to their number density in the 3D parameter space of F444W magnitude, F150W−F444W colour, and photometric redshift. In total, RUBIES observed ∼3000 targets across 1< z phot <10 with both the PRISM and G395M dispersers and ∼1500 targets at z phot >3 using only the G395M disperser. The RUBIES data reveal a highly diverse population of red sources that span a broad redshift range ( z spec ∼1−9), with photometric redshift scatter and an outlier fraction that are three times higher than for similarly bright sources that are less red. This diversity is not apparent from the photometric spectral energy distributions (SEDs). Only spectroscopy reveals that the SEDs encompass a mixture of galaxies with dust-obscured star formation, extreme line emission, a lack of star formation indicating early quenching, and luminous active galactic nuclei. As a first demonstration of our broader selection function we compared the stellar masses and rest-frame U − V colours of the red sources and our reference sample. We find that the red sources are typically more massive ( M * ∼10 10−11.5 M ⊙ ) across all redshifts. However, we also find that the most massive systems span a wide range in U − V colour. We describe our data reduction procedure and data quality, and we publicly release the reduced RUBIES data and vetted spectroscopic redshifts of the first half of the survey through the DAWN JWST Archive.

Astronomy and AstrophysicsVol. 697
National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, National Research Foundation, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Danmarks Grundforskningsfond, Deutsches Zentrum für Luft- und Raumfahrt, Bundesministerium für Wirtschaft und Energie, Staatssekretariat für Bildung, Forschung und Innovation
Openalex Percentile: Top 0%
Astronomy and Astrophysical Research
71.50
DOIOpen Access PDFOpenAlex
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