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Title: High-redshift Galaxy Candidates at z = 9–10 as Revealed by JWST Observations of WHL0137-08

We report the discovery of four galaxy candidates observed 450–600 Myr after the Big Bang with photometric redshifts betweenz∼ 8.3 and 10.2 measured using James Webb Space Telescope (JWST) NIRCam imaging of the galaxy cluster WHL0137−08 observed in eight filters spanning 0.8–5.0μm, plus nine Hubble Space Telescope filters spanning 0.4–1.7μm. One candidate is gravitationally lensed with a magnification ofμ∼ 8, while the other three are located in a nearby NIRCam module with expected magnifications ofμ≲ 1.1. Using SED fitting, we estimate the stellar masses of these galaxies are typically in the rangelogM/M= 8.3–8.7. All appear young, with mass-weighted ages <240 Myr, low dust contentAV< 0.15 mag, and specific star formation rates sSFR ∼0.25–10 Gyr−1for most. Onez∼ 9 candidate is consistent with an age <5 Myr and an sSFR ∼10 Gyr−1, as inferred from a strong F444W excess, implying [Oiii]+Hβrest-frame equivalent width ∼2000 Å, although an olderz∼ 10 object is also allowed. Anotherz∼ 9 candidate is lensed into an arc 2.″4 long with a magnification ofμ∼ 8. This arc is the most spatially resolved galaxy atz∼ 9 known to date, revealing structures ∼30 pc across. Follow-up spectroscopy of WHL0137−08 with JWST/NIRSpec will be useful to spectroscopically confirm these high-redshift galaxy candidates and to study their physical properties in more detail.

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DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Medium: X Size: Article No. 13
["Article No. 13"]
Sponsoring Org:
National Science Foundation
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