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Published March 10, 2025 | Version Published
Journal Article Open

The AURORA Survey: An Extraordinarily Mature, Star-forming Galaxy at z ∼ 7

Creators

  • 1. ROR icon University of California, Los Angeles
  • 2. ROR icon University of Kentucky
  • 3. ROR icon University of Arizona
  • 4. ROR icon University of California, Riverside
  • 5. ROR icon Carnegie Observatories
  • 6. ROR icon University of Geneva
  • 7. ROR icon University of Copenhagen
  • 8. ROR icon The University of Texas at Austin
  • 9. ROR icon Leiden University
  • 10. ROR icon Royal Observatory
  • 11. ROR icon University College London
  • 12. ROR icon Max Planck Institute for Extraterrestrial Physics
  • 13. ROR icon Swinburne University of Technology
  • 14. ROR icon University of California, Santa Cruz
  • 15. ROR icon University of California, Davis
  • 16. ROR icon University of Florida
  • 17. ROR icon University of Cambridge
  • 18. ROR icon California Institute of Technology

Abstract

We present the properties of a massive, large, dusty, metal-rich, star-forming galaxy at zspec = 6.73. GOODSN-100182 was observed with JWST/NIRSpec as part of the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) survey, and is also covered by public multiwavelength Hubble Space Telescope and JWST imaging. While the large stellar mass of GOODSN-100182 (∼1010 M⊙) was indicated prior to JWST, NIRCam rest-frame optical imaging now reveals the presence of an extended disk (reff ∼ 1.5 kpc). In addition, the NIRSpec R ∼ 1000 spectrum of GOODSN-100182 includes the detection of a large suite of rest-frame optical nebular emission lines ranging in wavelength from [O ii] λ3727 up to [N ii] λ6583. The ratios of Balmer lines suggest significant dust attenuation (E(B−V)gas=0.40−0.09+0.10), consistent with the red rest-frame UV slope inferred for GOODSN-100182 (β = −0.50 ± 0.09). The star formation rate based on dust-corrected Hα emission is log(SFR(Hα)/M⊙yr−1)=2.02−0.14+0.13, well above the z ∼ 7 star-forming main sequence in terms of specific star formation rate. Strikingly, the ratio of [N ii] λ6583/Hα emission suggests almost solar metallicity, as does the ratio ([O iii] λ5007/Hβ)/([N ii] λ6583/Hα) and the detection of the faint [Fe ii] λ4360 emission feature. Overall, the excitation and ionization properties of GOODSN-100182 more closely resemble those of typical star-forming galaxies at z ∼ 2–3 rather than z ∼ 7. Based on public spectroscopy of the GOODS-N field, we find that GOODSN-100182 resides within a significant galaxy overdensity, and is accompanied by a spectroscopically confirmed neighbor galaxy. GOODSN-100182 demonstrates the existence of mature, chemically enriched galaxies within the first billion years of cosmic time, whose properties must be explained by galaxy formation models.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

This work is based 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 NAS5-03127 for JWST. The specific observations analyzed can be accessed via DOI: 10.17909/hvne-7139. We also acknowledge support from NASA grant JWST-GO-01914. F.C. acknowledges support from a UKRI Frontier Research Guarantee Grant (PI: Cullen, grant reference EP/X021025/1). A.C.C. thanks the Leverhulme Trust for their support via a Leverhulme Early Career Fellowship. C.T.D., D.J.M., R.J.M., and J.S.D. acknowledge the support of the Science and Technology Facilities Council. J.S.D. also acknowledges the support of the Royal Society through a Royal Society Research Professorship. R.D. acknowledges support from the Wolfson Research Merit Award program of the U.K. Royal Society. K.G. acknowledges support from the Australian Research Council Laureate Fellowship FL180100060. M.K. acknowledges funding from the Dutch Research Council (NWO) through the award of the Vici grant VI.C.222.047 (project 2010007169). P.O. acknowledges the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00072, as well as from the Swiss National Science Foundation (SNSF) through project grant 200020_207349. A.J.P. was generously supported by a Carnegie Fellowship through the Carnegie Observatories. D.N. was funded by JWST-AR-01883.001.

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Additional details

Funding

National Aeronautics and Space Administration
JWST-GO-01914

Dates

Accepted
2025-01-27
Accepted
Available
2025-03-06
Published online

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Caltech groups
Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published