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Published February 20, 2025 | Version Published
Journal Article Open

The AURORA Survey: A New Era of Emission-line Diagrams with JWST/NIRSpec

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

Abstract

We present results on the emission-line properties of z = 1.4–7.5 star-forming galaxies in the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based on its depth, continuous wavelength coverage from 1 to 5 μm, and medium spectral resolution (R ∼ 1000), AURORA includes detections of a large suite of nebular emission lines spanning a broad range in rest-frame wavelength. We investigate the locations of AURORA galaxies in multiple different emission-line diagrams, including traditional BPT diagrams of [O iii]λ5007/Hβ versus [N ii]λ6583/Hα, [S ii]λλ6717, 6731/Hα, and [O i]λ6300/Hα, and the ionization–metallicity diagram of [O iii]λ5007/[O ii]λ3727 (O32) versus ([O iii]λ5007+[O ii]λ3727)/Hβ (R23). We also consider a bluer rest-frame ionization–metallicity diagram introduced recently to characterize z > 10 galaxies, [Ne iii]λ3869/[O ii]λ3727 versus ([Ne iii]λ3869+[O ii]λ3727)/Hδ, as well as longer-wavelength diagnostic diagrams extending into the rest-frame near-IR: [O iii]λ5007/Hβ versus [S iii]λλ9069, 9532/[S ii]λλ6717, 6731 (S32), and He iλ1.083 μm/Paγ and [S iii]λ9532/Paγ versus [Fe ii]λ1.257μm/Paβ. With a significant boost in signal-to-noise ratio and large, representative samples of individual galaxy detections, the AURORA emission-line diagrams presented here definitively confirm a physical picture in which chemically young, α-enhanced, massive stars photoionize the interstellar medium (ISM) in distant galaxies with a harder ionizing spectrum at fixed nebular metallicity than in their z ∼ 0 counterparts. We also uncover previously unseen evolution prior to z ∼ 2 in the [O iii]λ5007/Hβ versus [N ii]λ6583/Hα diagram, which motivates deep NIRSpec observations at even higher redshift. Finally, we present the first statistical sample of rest-frame near-IR emission-line diagnostics in star-forming galaxies at high redshift. In order to truly interpret rest-frame near-IR line ratios including [Fe ii]λ1.257 μm, we must obtain better constraints on dust depletion in the high-redshift ISM.

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 No. 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 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. We acknowledge useful insights from Claus Leitherer, and a constructive and helpful report from an anonymous referee. Finally, we thank members of the JADES team for assistance with target selection in the GOODS-N field.

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2407.00157 (arXiv)
Is supplemented by
Dataset: 10.17909/hvne-7139 (DOI)

Funding

National Aeronautics and Space Administration
NAS5-03127
National Aeronautics and Space Administration
JWST-GO-01914
UK Research and Innovation
EP/X021025/1
Leverhulme Trust
Science and Technology Facilities Council
Royal Society
Australian Research Council
FL180100060
Dutch Research Council
VI.C.222.047
State Secretariat for Education, Research and Innovation
MB22.00072
Swiss National Science Foundation
200020_207349
Carnegie Observatories

Dates

Accepted
2025-01-21
Available
2025-02-19
Published

Caltech Custom Metadata

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