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

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

We present the properties of a massive, large, dusty, metal-rich, star-forming galaxy at z _spec  = 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...

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Main Authors: Alice E. Shapley, Ryan L. Sanders, Michael W. Topping, Naveen A. Reddy, Anthony J. Pahl, Pascal A. Oesch, Danielle A. Berg, Rychard J. Bouwens, Gabriel Brammer, Adam C. Carnall, Fergus Cullen, Romeel Davé, James S. Dunlop, Richard S. Ellis, N. M. Förster Schreiber, Steven R. Furlanetto, Karl Glazebrook, Garth D. Illingworth, Tucker Jones, Mariska Kriek, Derek J. McLeod, Ross J. McLure, Desika Narayanan, Max Pettini, Daniel Schaerer, Daniel P. Stark, Charles C. Steidel, Mengtao Tang, Leonardo Clarke, Callum T. Donnan, Emily Kehoe
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Galaxy formation
Galaxy evolution
High-redshift galaxies
Emission line galaxies
Online Access:https://doi.org/10.3847/1538-4357/adaf98
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Summary:We present the properties of a massive, large, dusty, metal-rich, star-forming galaxy at z _spec  = 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 (∼10 ^10 M _⊙ ) was indicated prior to JWST, NIRCam rest-frame optical imaging now reveals the presence of an extended disk ( r _eff  ∼ 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 ] λ 3727 up to [N ii ] λ 6583. The ratios of Balmer lines suggest significant dust attenuation ( $E{(B-V)}_{{\rm{gas}}}=0.4{0}_{-0.09}^{+0.10}$ ), 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 H α emission is $\mathrm{log}(\mathrm{SFR(H}\alpha )/{M}_{\odot }\,{\mathrm{yr}}^{-1})=2.0{2}_{-0.14}^{+0.13}$ , well above the z  ∼ 7 star-forming main sequence in terms of specific star formation rate. Strikingly, the ratio of [N ii ] λ 6583/H α emission suggests almost solar metallicity, as does the ratio ([O iii ] λ 5007/H β )/([N ii ] λ 6583/H α ) and the detection of the faint [Fe ii ] λ 4360 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.
ISSN:1538-4357

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