A Comprehensive Study of Galaxies at z ∼ 9–16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch

Harikane, Yuichi; Ouchi, Masami; Oguri, Masamune; Ono, Yoshiyasu; Nakajima, Kengo; Isobe, Yuki; Umeda, Hiroya; Mawatari, Ken; Zhang, Yechi

doi:10.3847/1538-4365/acaaa9

Cited by 273 publications

(263 citation statements)

References 170 publications

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“…At z ∼ 12, where we identified three candidates, our number density estimate is slightly larger than the two JWST studies (Harikane et al 2023;Donnan et al 2023 candidates in one field while none in another field. The same is true in Donnan et al (2023), where they identify two candidates at z ∼ 12 in the SMACS field, while none in the three of the CEERS's pointings.…”

Section: Number Densities Of High-redshift Candidatescontrasting

confidence: 65%

Physical Characterization of Early Galaxies in the Webb’s First Deep Field SMACS J0723.3-7327

Morishita

Stiavelli

2023

ApJL

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This paper highlights initial photometric analyses of JWST NIRCam imaging data in the sightline of SMACS0723, aiming to identify galaxies at redshift z > 7. By applying a conservative Lyman-break selection followed by photometric-redshift analysis and visual inspection, we identify four F090W-dropout and two F150W-dropout sources, three of which were recently confirmed in an independent spectroscopic analysis to z = 7.663, 7.665, and 8.499. We then supplement our sample with a photometric-redshift selection, and identify five additional candidates at 7 < z phot < 13. The NIRCam images clearly resolve all sources and reveal their subgalactic components that were not resolved/detected in the previous imaging by Hubble Space Telescope. Our spectral energy distribution analysis reveals that the selected galaxies are characterized by young stellar populations (median age of ∼50 Myr) of subsolar metallicity (∼0.2 Z ⊙) and little dust attenuation (A V ∼ 0.5). In several cases, we observe extreme Hβ+[O iii] lines being captured in the F444W band and seen as color excess, which is consistent with their observed high star formation rate surface density. Eight of the 11 sources identified in this study appear in at least one of the recent studies (Adams et al.; Atek et al.; Donnan et al.; Harikane et al.; Yan et al.) of the same fields, implying the high fidelity of our selection. We crossmatch all high-z galaxy candidates presented in the five studies with our catalog and discuss the possible causes of discrepancy in the final lists.

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Section: Number Densities Of High-redshift Candidatescontrasting

confidence: 65%

Physical Characterization of Early Galaxies in the Webb’s First Deep Field SMACS J0723.3-7327

Morishita

Stiavelli

2023

ApJL

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“…Now, z ∼ 3-6 dusty galaxies may be contaminating z > 7-10 JWST samples. A contributing factor to this contamination is that both populations have similar, and uncertain, number densities: DSFGs at z ∼ 3-6 have volume number densities n ∼ 10 −5 -10 −6 Mpc −3 (Koprowski et al 2017;Michałowski et al 2017;Rowan-Robinson et al 2018;Dudzevičiūtė et al 2020;Gruppioni et al 2020;Long et al 2022;Manning et al 2022), similar to early measurements of bright z > 10 LBGs (Bouwens et al 2022;Finkelstein et al 2022a;Harikane et al 2023;Naidu et al 2022a). Disentangling these two populations is therefore also crucial for reducing uncertainties in their respective number densities, which are currently inflated by sample purity (e.g., Bouwens et al 2022).…”

Section: Introductionmentioning

confidence: 76%

“…Based on the first analysis of JWST deep field observations at 5σ point-source depths at ∼28 −29 mag, the projected sky density of candidates at z > 10 is approximately 350 ± 120 deg −2 (Donnan et al 2023;Finkelstein et al 2022a;Harikane et al 2023;Naidu et al 2022a). Although preliminary, these source counts represent the population that could potentially be contaminated by low −z dusty interlopers.…”

Section: Resultsmentioning

confidence: 99%

“…A major objective baked into the design of JWST is detecting the light from the first galaxies residing at ultrahigh redshifts (z > 10). Delivering on its promise, more than 30 galaxy candidates with photometric redshift solutions favoring z > 10 were identified within the first months of publicly available data (Bradley et al 2022;Donnan et al 2023;Finkelstein et al 2022a;Harikane et al 2023;Naidu et al 2022a;Yu-Yang Hsiao et al 2022). Assessing the fidelity of these samples is critical, particularly because the statistics assuming current z > 10-15 candidates are real may or may not violate ΛCDM predictions (Boylan-Kolchin 2022; Labbe et al 2022;Maio & Viel 2022;Naidu et al 2022a).…”

Section: Introductionmentioning

confidence: 99%

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Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry

McKinney

Finnerty

Casey

et al. 2023

ApJL

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Selecting the first galaxies at z > 7 − 10 from JWST surveys is complicated by z < 6 contaminants with degenerate photometry. For example, strong optical nebular emission lines at z < 6 may mimic JWST/NIRCam photometry of z > 7–10 Lyman-break galaxies (LBGs). Dust-obscured 3 < z < 6 galaxies in particular are potentially important contaminants, and their faint rest-optical spectra have been historically difficult to observe. A lack of optical emission line and continuum measures for 3 < z < 6 dusty galaxies now makes it difficult to test their expected JWST/NIRCam photometry for degenerate solutions with NIRCam dropouts. Toward this end, we quantify the contribution by strong emission lines to NIRCam photometry in a physically motivated manner by stacking 21 Keck II/NIRES spectra of hot, dust-obscured, massive ( log M * / M ⊙ ≳ 10 – 11 ) and infrared (IR) luminous galaxies at z ∼ 1–4. We derive an average spectrum and measure strong narrow (broad) [O iii]5007 and Hα features with equivalent widths of 130 ± 20 Å (150 ± 50 Å) and 220 ± 30 Å (540 ± 80 Å), respectively. These features can increase broadband NIRCam fluxes by factors of 1.2 − 1.7 (0.2–0.6 mag). Due to significant dust attenuation (A V ∼ 6), we find Hα+[N ii] to be significantly brighter than [O iii]+Hβ and therefore find that emission-line dominated contaminants of high −z galaxy searches can only reproduce moderately blue perceived UV continua of S λ ∝ λ β with β > − 1.5 and z > 4. While there are some redshifts (z ∼ 3.75) where our stack is more degenerate with the photometry of z > 10 LBGs at λ rest ∼ 0.3–0.8 μm , redder filter coverage beyond λ obs > 3.5 μm and far-IR/submillimeter follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at z ∼ 3–6 and LBGs at z > 10.

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“…With the successful launch of the James Webb Space Telescope (JWST), astronomy has entered an exciting period of extending the frontiers of what we know about the universe. Initial results from JWST imaging hint at a surprising abundance of massive galaxies already briefly after cosmic dawn, at redshifts z  10 (e.g., Finkelstein et al 2022;Harikane et al 2023;Labbe et al 2022;Naidu et al 2022;Adams et al 2023;Atek et al 2023). If confirmed by spectroscopic followup, such early emergence of massive galaxies may seriously challenge the ΛCDM standard model of cosmological structure formation (Boylan-Kolchin 2022), with no obvious way to accelerate early galaxy formation (e.g., Klypin et al 2021;Liu & Bromm 2022).…”

Section: Introductionmentioning

confidence: 99%

Probing the Nature of the First Galaxies with JWST and ALMA

Rossi

2023

ApJL

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By implementing a model of primordial dust emission, we predict dust-continuum fluxes for massive galaxy sources similar to those recently detected by James Webb Space Telescope (JWST) at z ≳ 7. Current upper flux limits, obtained with Atacama Large Millimeter/submillimeter Array (ALMA) for some of these sources, can constrain the gas metallicity and dust fraction of the first galaxies. Encouragingly, if assuming expected properties for typical first galaxies (i.e., dust-to-metal mass ratio: D/M = 5 × 10−3, gas metallicity: Z g = 5 × 10−3 Z ☉, star formation efficiency: η = 0.01), model far-infrared (FIR) fluxes are consistent with current upper flux limits inferred from ALMA bands 6 and 7 (≲104 nJy). Such low D/M values and metallicities are in agreement with some scenarios proposed in the literature to explain the nondetection of the FIR dust continuum for high-z JWST galaxy candidates. On the other hand, higher values of model parameters D/M (≳0.06) and Z g (≳5 × 10−2 Z ☉) are ruled out by observational data, unless a higher η is assumed. According to our findings, ALMA multiband observations could constrain the dust chemistry and dust grain size distribution in the early universe. In this context, future observational challenges would involve not only reaching higher FIR sensitivities, but also increasing the wavelength coverage by exploring distinct ALMA bands.

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A Comprehensive Study of Galaxies at z ∼ 9–16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch

Cited by 273 publications

References 170 publications

Physical Characterization of Early Galaxies in the Webb’s First Deep Field SMACS J0723.3-7327

Physical Characterization of Early Galaxies in the Webb’s First Deep Field SMACS J0723.3-7327

Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry

Probing the Nature of the First Galaxies with JWST and ALMA

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