JWST and ALMA Multiple-Line Study in and around a Galaxy at $z=8.496$: Optical to FIR Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape

Fujimoto, Seiji; Ouchi, Masami; Nakajima, Kengo; Harikane, Yuichi; Isobe, Yuki; Brammer, Gabriel; Oguri, Masamune; Giménez-Arteaga, Clara; Heintz, K. E.; Kokorev, Vasily; Bauer, F. E.; Ferrara, Andrea; Kojima, Takashi; Lagos, Claudia del P.; Laura, Sommovigo; Shimasaku, Kazuhiro; Hatsukade, Bunyo; Kohno, Kotaro; Sun, Fengwu; Valentino, Francesco; Watson, Derrick G.; Fudamoto, Yoshinobu; Inoue, Akio; González-López, Jorge; Koekemoer, Anton M.; Knudsen, K. K.; Lee, Minju; Magdis, G.; Richard, Johan; Strait, Victoria B.; Sugahara, Yuma; Tamura, Motohide; Toft, Sune; Umehata, Hideki; Walth, Gregory

doi:10.48550/arxiv.2212.06863

“…33 Indeed, early observations from JWST have already identified candidates for galaxies at z  15 (Finkelstein et al 2022b;Curtis-Lake et al 2023;Donnan et al 2023;Robertson et al 2023). Spectroscopy from JWST of galaxies at z ∼ 8-9 shows emission lines from heavy elements that appear to require metallicities of ≈5%-10% Z e (Arellano-Córdova et al 2022;Fujimoto et al 2022;Heintz et al 2023;Langeroodi et al 2022;Matthee et al 2022;Schaerer et al 2022;Trump et al 2023;Curti et al 2023;Katz et al 2023), implying these galaxies have experienced at least one (and probably multiple) generation(s) of previous stars. This is consistent with earlier detections of metal lines in z > 6 galaxies from ground-based telescopes (e.g., Stark et al 2017;Hutchison et al 2019).…”

Section: Introductionmentioning

confidence: 99%

CEERS Key Paper. V. Galaxies at 4 < z < 9 Are Bluer than They Appear–Characterizing Galaxy Stellar Populations from Rest-frame ∼1 μm Imaging

Papovich

¹

,

Cole

²

,

Yang

³

et al. 2023

ApJL

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We present results from the Cosmic Evolution Early Release Survey on the stellar population parameters for 28 galaxies with redshifts 4 < z < 9 using imaging data from the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) combined with data from the Hubble Space Telescope and the Spitzer Space Telescope. The JWST/MIRI 5.6 and 7.7 μm data extend the coverage of the rest-frame spectral energy distribution to nearly 1 μm for galaxies in this redshift range. By modeling the galaxies’ SEDs the MIRI data show that the galaxies have, on average, rest-frame UV (1600 Å)—I-band colors 0.4 mag bluer than derived when using photometry that lacks MIRI. Therefore, the galaxies have lower ratios of stellar mass to light. The MIRI data reduce the stellar masses by 〈 Δ log M * 〉 = 0.25 dex at 4 < z < 6 and 0.37 dex at 6 < z < 9. This also reduces the star formation rates (SFRs) by 〈ΔlogSFR〉 = 0.14 dex at 4 < z < 6 and 0.27 dex at 6 < z < 9. The MIRI data also improve constraints on the allowable stellar mass formed in early star formation. We model this using a star formation history that includes both a “burst” at z f = 100 and a slowly varying (“delayed-τ”) model. The MIRI data reduce the allowable stellar mass by 0.6 dex at 4 < z < 6 and by ≈1 dex at 6 < z < 9. Applying these results globally, this reduces the cosmic stellar-mass density by an order of magnitude in the early Universe (z ≈ 9). Therefore, observations of rest-frame ≳1 μm are paramount for constraining the stellar-mass buildup in galaxies at very high redshifts.

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“…There have been multiple works on these targets, albeit always from an integrated perspective (e.g., Arellano-Córdova et al 2022;Brinchmann 2022;Carnall et al 2023;Curti et al 2022;Fujimoto et al 2022;Heintz et al 2023;Rhoads et al 2023;Schaerer et al 2022;Tacchella et al 2022;Trump et al 2023). These papers derive different stellar masses, some of them with extremely young ages of the stellar population.…”

Section: Introductionmentioning

confidence: 99%

Spatially Resolved Properties of Galaxies at 5 < z < 9 in the SMACS 0723 JWST ERO Field

Giménez-Arteaga

¹

,

Oesch

²

,

Brammer

³

et al. 2023

ApJ

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We present the first spatially resolved measurements of galaxy properties in the JWST ERO SMACS 0723 field. We perform a comprehensive analysis of five 5 < z < 9 galaxies with spectroscopic redshifts from NIRSpec observations. We perform spatially resolved spectral energy distribution fitting with Bagpipes, using six NIRCam imaging bands spanning the wavelength range 0.8–5 μm. This approach allows us to study the internal structure and assembly of the first generations of galaxies. We find clear gradients both in the empirical color maps and in most of the estimated physical parameters. We find regions of considerably different specific star formation rates across each galaxy, which points to very bursty star formation happening on small scales, not galaxy-wide. The integrated light is dominated by these bursty regions, which exhibit strong line emission, with the equivalent width of [O iii]+Hβ reaching up to ∼3000–4000 Å rest frame. Studying these galaxies in an integrated approach yields extremely young inferred ages of the stellar population (<10 Myr), which outshine older stellar populations that are only distinguishable in the spatially resolved maps. This leads to inferring ∼0.5–1 dex lower stellar masses by using single-aperture photometry, when compared to resolved analyses. Such systematics would have strong implications in the shape and evolution of the stellar mass function at these early times, particularly while samples are limited to small numbers of the brightest candidates. Furthermore, the evolved stellar populations revealed in this study imply an extended process of early galaxy formation that could otherwise be hidden behind the light of the most recently formed stars.

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“…Diffraction losses within NIRSpec (Jakobsen et al 2022), which are not included in the second approach, could also be a possible reason for the difference. An extended [O III]+Hβ structure has been identified around a lensed galaxy at z = 8.5 (Fujimoto et al 2022b), and the differential spatial distribution between the ionized gas and the underlying continuum emission is also another unknown uncertainty in both approaches. We thus caution the readers that additional uncertainty might exist in the measurements due to the slit-loss correction steps.…”

Section: Slitloss Correctionmentioning

confidence: 99%

“…This is because of the potential uncertainty in the slit-loss correction (Section 3.4). Also, an extended [O III]+Hβ structure has been recently reported around a lensed galaxy at z = 8.5, which might make the Hβ-based SFR measurement be overestimated by counting the Hβ emission caused by other physical mechanisms such as powerful outflows (Fujimoto et al 2022b).…”

Section: Properties Of Galaxies At Z = 8-9mentioning

confidence: 99%

“…This is because of the potential uncertainty in the slit-loss correction (Section 3.4). Also, an extended [O III]+Hβ structure has been recently reported around a lensed galaxy at z = 8.5, which might make the Hβ-based SFR measurement be overestimated by counting the Hβ emission caused by other physical mechanisms such as powerful outflows(Fujimoto et al 2022b).In Figure5, we find that our NIRCam-selected sample (redfilled circles) has a SFR-M star relation generally consistent with the recent JWST results for lensed galaxies at z = 7-10 (magenta squares) down to ∼7 × 10 7 M e . These galaxies from our and recent JWST studies are generally less star-forming and less massive than the HST-selected bright galaxies at similar redshifts (red open pentagons).…”

mentioning

confidence: 99%

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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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JWST and ALMA Multiple-Line Study in and around a Galaxy at $z=8.496$: Optical to FIR Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape

Cited by 12 publications

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CEERS Key Paper. V. Galaxies at 4 < z < 9 Are Bluer than They Appear–Characterizing Galaxy Stellar Populations from Rest-frame ∼1 μm Imaging

CEERS Key Paper. V. Galaxies at 4 < z < 9 Are Bluer than They Appear–Characterizing Galaxy Stellar Populations from Rest-frame ∼1 μm Imaging

Spatially Resolved Properties of Galaxies at 5 < z < 9 in the SMACS 0723 JWST ERO Field

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

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