Unscrambling the lensed galaxies in JWST images behind SMACS0723

Pascale, Massimo; Frye, Brenda; Diego, J. M.; Furtak, Lukas J.; Zitrin, Adi; Broadhurst, Tom; Conselice, Christopher J.; Dai, Liang; Ferreira, Leonardo; Adams, Nathan; Lim, Jeremy; Meena, Ashish; Wilkins, Stephen M.; Bhatawdekar, Rachana; Windhorst, Rogier A.

doi:10.48550/arxiv.2207.07102

Cited by 17 publications

(39 citation statements)

References 47 publications

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“…Additional models for this cluster have been recently published by Pascale et al (2022) and Caminha et al (2022). A full assessment of the systematics introduced by the adoption of different lensing models is far beyond the scope of this work.…”

Section: Magnification Factorsmentioning

confidence: 96%

The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8

Curti,

D'Eugenio,

Carniani

et al. 2022

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We analyse the chemical properties of three z∼ 8 galaxies behind the galaxy cluster SMACS J0723.3-7327, observed as part of the Early Release Observations programme of the James Webb Space Telescope (JWST). Exploiting [O ]𝜆4363 auroral line detections in NIRSpec spectra, we robustly apply the direct 𝑇 e method for the very first time at such high redshift, measuring metallicities ranging from extremely metal poor (12+log(O/H)≈ 7) to about one-third solar. We also discuss the excitation properties of these sources, and compare them with local strong-line metallicity calibrations. We find that none of the considered diagnostics match simultaneously the observed relations between metallicity and strong-line ratios for the three sources, implying that a proper re-assessment of the calibrations may be needed at these redshifts. On the mass-metallicity plane, the two galaxies at 𝑧 ∼ 7.6 (log(M * /M ) = 8.1, 8.7) have metallicities that are consistent with the extrapolation of the mass-metallicity relation at z∼2-3, while the least massive galaxy at 𝑧 ∼ 8.5 (log(M * /M ) = 7.8) shows instead a significantly lower metallicity . The three galaxies show different level of offset relative to the Fundamental Metallicity Relation, with two of them (at z∼ 7.6) being marginally consistent, while the z∼ 8.5 source deviating significantly, being probably far from the smooth equilibrium between gas flows, star formation and metal enrichment in place at later epochs.

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Section: Magnification Factorsmentioning

confidence: 96%

The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8

Curti,

D'Eugenio,

Carniani

et al. 2022

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“…In this paper we focus on the NIRSpec observations of the 5 galaxies at z > 5 that were presented by Carnall et al (2022). All 5 of these galaxies are lensed by the foreground cluster: ID 4590 (z = 8.5) has a magnification factor of 8, while the other 4 galaxies have more modest magnification factors of 1.5-2 (using the parametric model of Pascale et al 2022). SMACS 0723 was also observed with NIRISS spectroscopy and with NIRCam and MIRI imaging although we do not use those data in this work.…”

Section: Observationsmentioning

confidence: 99%

The Physical Conditions of Emission-Line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations

Trump¹,

Haro²,

Simons³

et al. 2022

Preprint

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We present rest-frame optical emission-line flux ratio measurements for five z > 5 galaxies observed by the James Webb Space Telescope Near-Infared Spectrograph (NIRSpec) in the SMACS 0723 Early Release Observations. We add several quality-control and post-processing steps to the NIRSpec pipeline reduction products in order to ensure reliable relative flux calibration of emission lines that are closely separated in wavelength, despite the uncertain absolute spectrophotometry of the current version of the reductions. Compared to z ∼ 2 galaxies in the literature, the z > 5 galaxies have similar [O III]λ5008/Hβ ratios, slightly higher (∼0.5 dex) [O III]λ4364/Hγ ratios and much higher (∼1 dex) [Ne III]λ3870/[O II]λ3728 ratios. We compare the observations to MAPPINGS V photoionization models and find that the measured [Ne III]λ3870/[O II]λ3728, [O III]λ4364/Hγ, and [O III]λ5008/Hβ emission-line ratios are consistent with an interstellar medium that has very high ionization (log(Q) 8 − 9, units of cm s −1 ), low metallicity (Z/Z 0.1), and very high pressure (log(P/k) 8 − 9, units of cm −3 ). The combination of [O III]λ4364/Hγ and [O III]λ(4960 + 5008)/Hβ line ratios indicate very high electron temperatures of 4.1 < log(T e ) < 4.5, further implying metallicities of Z/Z 0.1 with the application of low-redshift calibrations for "direct" metallicities. These observations represent a tantalizing new view of the physical conditions of the interstellar medium in galaxies at cosmic dawn.

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“…Interestingly, two objects (6355 and 10612) display almost identical redshifts. These objects are however far from the centre of the cluster, and are not listed as multiple images in any currently available lensing analysis of this field (Mahler et al 2022;Pascale et al 2022;Caminha et al 2022).…”

Section: Spectroscopic Redshift Determinationmentioning

confidence: 99%

A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses and star-formation histories

Carnall¹,

Begley²,

McLeod³

et al. 2022

Preprint

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We present a first-look analysis of the JWST ERO data in the SMACS J0723.3-7327 cluster field. We begin by reporting 10 new spectroscopic redshifts from 𝜆 obs = 1.8 − 5.2𝜇m NIRSpec medium-resolution (𝑅 = 𝜆/Δ𝜆 = 1000) data. These are all determined via multiple high-SNR emission line detections, with 5 objects at 1 < 𝑧 < 3 displaying multiple rest-frame near-infrared Hydrogen Paschen lines, and 5 objects at 5 < 𝑧 < 9 displaying rest-frame optical Oxygen and Hydrogen Balmer lines. For the 5 higher-redshift galaxies we extract fluxes in 6 NIRCam bands spanning 𝜆 obs = 0.8 − 5𝜇m and perform spectral energy distribution fitting using these data in combination with existing HST photometry. The 7 < 𝑧 < 9 objects exhibit a U-shaped pattern across the F277W, F356W and F444W bands, indicating the presence of a Balmer break seen in emission (Balmer jump) and high-equivalent-width [O ] emission. This is indicative of an extremely young stellar population, with the bulk of the current mass having formed within the past 10 Myr. We report robust stellar masses and mean stellar ages from our spectral fitting, with the four 𝑧 > 6 galaxies exhibiting low stellar masses from log 10 (𝑀 * /M ) = 7.4 − 8.6 and correspondingly young mean stellar ages of only a few Myr. This work highlights the critical importance of combining large upcoming NIRCam surveys with NIRSpec follow-up to measure the spectroscopic redshifts necessary to robustly constrain physical parameters.

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Unscrambling the lensed galaxies in JWST images behind SMACS0723

Cited by 17 publications

References 47 publications

The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8

The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8

The Physical Conditions of Emission-Line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations

A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses and star-formation histories

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