A magnified compact galaxy at redshift 9.51 with strong nebular emission lines

Williams, Hayley; Kelly, Patrick L.; Chen, Wenlei; Brammer, Gabriel; Zitrin, Adi; Treu, Tommaso; Scarlata, Claudia; Koekemoer, Anton M.; Oguri, Masamune; Lin, Yu-Heng; Diego, J. M.; Nonino, M.; Hjorth, J.; Langeroodi, Danial; Broadhurst, Tom; Rogers, Noah S. J.; Pérez-Fournón, I.; Foley, R. J.; Filippenko, A. V.; Strolger, Louis-Gregory; Pierel, Justin; Poidevin, F.; Yang, Lilan

doi:10.1126/science.adf5307

“…In addition to detailed investigations of remarkable individual NIRSpec spectra at high redshift (e.g., Williams et al 2023;Bunker et al 2023;Curti et al 2023), JWST spectra are also starting to be used for analysis of the chemical abundances of samples of distant galaxies. Matthee et al (2022) present NIRCam grism observations of [O III]/Hβ in concert with stellar mass estimates for a sample of 117 [O III]-emitting galaxies at 5.3 z 6.9.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent remarkable NIRSpec spectra have revealed the rest-optical nebular properties of individual galaxies at z = 9.5 (Williams et al 2023) and, now, z = 10.6 (Bunker et al 2023). The low metallicities of the z > 8 targets observed by JWST, given their stellar masses and SFRs, suggest that they do not fall on the FMR that describes galaxies at z 3 (Langeroodi et al 2022;Williams et al 2023;Curti et al 2023). However, it is challenging to draw broad conclusions from such a small sample, which may or may not be representative of the full population at these redshifts, and questions remain about which calibrations can be used to accurately infer metallicity at such high redshifts.…”

Section: Introductionmentioning

confidence: 96%

“…Even the very first NIRSpec spectroscopic data released to the public revealed the promise of JWST for estimating the gas-phase chemical abundances of star-forming galaxies at z ∼ 7.5-8.5 (e.g., Arellano-Córdova et al 2022;Curti et al 2023). Subsequent remarkable NIRSpec spectra have revealed the rest-optical nebular properties of individual galaxies at z = 9.5 (Williams et al 2023) and, now, z = 10.6 (Bunker et al 2023). The low metallicities of the z > 8 targets observed by JWST, given their stellar masses and SFRs, suggest that they do not fall on the FMR that describes galaxies at z 3 (Langeroodi et al 2022;Williams et al 2023;Curti et al 2023).…”

Section: Introductionmentioning

confidence: 99%

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JWST/NIRSpec Measurements of the Relationships between Nebular Emission-line Ratios and Stellar Mass at z ∼ 3–6

Shapley

¹

,

Reddy

²

,

Topping

³

et al. 2023

ApJL

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We analyze the rest-optical emission-line ratios of star-forming galaxies at 2.7 ≤ z < 6.5 drawn from the Cosmic Evolution Early Release Science (CEERS) Survey and their relationships with stellar mass (M *). Our analysis includes both line ratios based on the [N ii] λ6583 feature ([N ii] λ6583/Hα, ([O iii] λ5007/Hβ)/([N ii] λ6583/Hα) (O3N2), and [N ii] λ6583/[O ii] λ3727) and those featuring α-elements ([O iii] λ5007/Hβ, [O iii] λ5007/[O ii] λ3727 (O32), ([O iii] λλ4959, 5007 + [O ii] λ3727)/Hβ (R23), and [Ne iii] λ3869/[O ii] λ3727). Given the typical flux levels of [N ii] λ6583 and [Ne iii] λ3869, which are undetected in the majority of individual CEERS galaxies at 2.7 ≤ z < 6.5, we construct composite spectra in bins of M * and redshift. Using these composite spectra, we compare the relationships between emission-line ratios and M * at 2.7 ≤ z < 6.5 with those observed at lower redshift. While there is significant evolution toward higher excitation (e.g., higher [O iii] λ5007/Hβ, O32, O3N2) and weaker nitrogen emission (e.g., lower [N ii] λ6583/Hα and [N ii] λ6583/[O ii] λ3727) between z ∼ 0 and z ∼ 3, we find in most cases that there is no significant evolution in the relationship between line ratio and M * beyond z ∼ 3. The [Ne iii] λ3869/[O ii] λ3727 ratio is anomalous in showing evidence for significant elevation at 4.0 ≤ z < 6.5 at fixed mass, relative to z ∼ 3.3. Collectively, however, our empirical results suggest no significant evolution in the mass–metallicity relationship at 2.7 ≤ z < 6.5. Representative galaxy samples and metallicity calibrations based on existing and upcoming JWST/NIRSpec observations will be required to translate these empirical scaling relations into ones tracing chemical enrichment and gas cycling and to distinguish among descriptions of feedback in galaxy formation simulations at z > 3.

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“…We find a remarkably small size of r 30 hl 5 7 =  pc for MACS0417-z5BBG, where r hl is the half-light radius, and a best-fitting Sérsic index of ∼8, which is consistent with a compact bulge morphology. While new results on rest-UV sizes at z ∼ 5 with JWST are sparse, this size is much smaller than average sizes reported for galaxies at z  7 (e.g., Ono et al 2022;Yang et al 2022) but similar to some of the single-object discoveries found so far (e.g., Williams et al 2023).…”

Section: Sizementioning

confidence: 41%

An Extremely Compact, Low-mass Galaxy on its Way to Quiescence at z = 5.2

Strait

¹

,

Brammer

²

,

Muzzin

³

et al. 2023

ApJL

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We report the discovery of a low-mass z = 5.200 ± 0.002 galaxy that is in the process of ceasing its star formation. The galaxy, MACS0417-z5BBG, is multiply imaged with magnification factors ∼40 by the galaxy cluster MACS J0417.5-1154, observed as part of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS). Using observations of MACS0417-z5BBG with a JWST/NIRSpec Prism spectrum and NIRCam imaging, we investigate the mechanism responsible for the cessation of star formation of the galaxy and speculate about possibilities for its future. Using spectrophotometric fitting, we find a remarkably low stellar mass of M * = 4.3 ± 0.8 0.9 × 10 7 M ⊙ , less than 1% of the characteristic stellar mass at z ∼ 5. We measure a delensed rest-UV half-light radius in the source plane of 30 ± 5 7 pc and measure a star formation rate from Hα of 0.14 ± 0.12 0.17 M ⊙ yr−1. We find that under the assumption of a double power-law star formation history, MACS0417-z5BBG has seen a recent rise in star formation, peaking ∼10–30 Myr ago and declining precipitously since then. Together, these measurements reveal a low-mass, extremely compact galaxy which is in the process of ceasing star formation. We investigate the possibilities of mechanisms that have led to the cessation of star formation in MACS0417-z5BBG, considering stellar and active galactic nuclei (AGN) feedback and environmental processes. We can likely rule out most environmental processes but leave open the possibility of a low-mass AGN that does not leave a broad-line imprint on the spectrum or that MACS0417-z5BBG could be a star-forming galaxy in the lull of a bursty star formation history.

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“…Figure5presents the SFR-M star relation. For comparison, we show the main sequence estimated at z = 2, and z = 6(Iyer et al 2018), recent JWST results for the sources spectroscopically confirmed at z = 7 − 13 (Curtis-Lake et al 2023;Heintz et al 2022;Roberts-Borsani et al 2022;Robertson et al 2023;Tacchella et al 2023;Williams et al 2023), the HSTselected, brighter LBGs (M UV ; − 21.5) spectrosopically confirmed at z = 8 − 9 in CEERS(R.Larson et al 2023, in preparation), and the 16th-84th percentile of the distribution of simulated galaxies at z = 7 − 8(Behroozi et al 2019(Behroozi et al , 2020Nelson et al 2019;Yung et al 2019bYung et al , 2022Wilkins et al 2023Wilkins et al , 2022. Note that we use the SED-based SFR estimate (Section 3.5), instead of using the Hβ line.…”

mentioning

confidence: 89%

CEERS Spectroscopic Confirmation of NIRCam-selected z ≳ 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of Their Properties

Fujimoto

¹

,

Haro

²

,

Dickinson

³

et al. 2023

ApJL

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We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 − 13 and M UV ∈ [ −21, −18] newly identified in NIRCam images in the Cosmic Evolution Early Release Science Survey. We confirm emission line redshifts for 7 galaxies at z = 7.762–8.998 using spectra at ∼1–5 μm either with the NIRSpec prism or its three medium-resolution (R ∼ 1000) gratings. For z ≃ 9 photometric candidates, we achieve a high confirmation rate of ≃90%, which validates the classical dropout selection from NIRCam photometry. No robust emission lines are identified in three galaxy candidates at z > 10, where the strong [O iii] and Hβ lines would be redshifted beyond the wavelength range observed by NIRSpec, and the Lyα continuum break is not detected with the sensitivity of the current data. Compared with Hubble Space Telescope-selected bright galaxies (M UV ≃ −22) that are similarly spectroscopically confirmed at z ≃ 8 − 9, these NIRCam-selected galaxies are characterized by lower star formation rates (SFRs; SFR ≃ 4 M ⊙ yr−1) and lower stellar masses (≃108 M ⊙), but with higher specific SFR (≃40 Gyr−1), higher [O iii]+Hβ equivalent widths (≃1100 Å), and elevated production efficiency of ionizing photons ( log ( ξ ion / Hz erg − 1 ) ≃ 25.8 ) induced by young stellar populations (<10 Myr) accounting for ≃20% of the galaxy mass, highlighting the key contribution of faint galaxies to cosmic reionization. Taking advantage of the homogeneous selection and sensitivity, we also investigate metallicity and ISM conditions with empirical calibrations using the [O iii]5008/Hβ ratio. We find that galaxies at z ≃ 8 − 9 have higher SFRs and lower metallicities than galaxies at similar stellar masses at z ≃ 2 − 6, which is generally consistent with the current galaxy formation and evolution models.

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A magnified compact galaxy at redshift 9.51 with strong nebular emission lines

Cited by 59 publications

References 79 publications

JWST/NIRSpec Measurements of the Relationships between Nebular Emission-line Ratios and Stellar Mass at z ∼ 3–6

JWST/NIRSpec Measurements of the Relationships between Nebular Emission-line Ratios and Stellar Mass at z ∼ 3–6

An Extremely Compact, Low-mass Galaxy on its Way to Quiescence at z = 5.2

CEERS Spectroscopic Confirmation of NIRCam-selected z ≳ 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of Their Properties

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