Journal Article

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

Larson, Rebecca L, Hutchison, Taylor A, Furtak, Lukas J, Bradley, Larry D, Jung, Intae, Trenti, M, Brammer, Gabriel, Andrade-Santos, Felipe, Zitrin, Adi, Carnall, Adam, Diego, Jose M, Fujimoto, Seiji, Coe, Dan, Bhatawdekar, Rachana, Vanzella, Eros, Windhorst, Rogier A, McCandliss, Stephan, Oguri, Masamune, Welch, Brian, Sharon, Keren, Postman, Marc, Frye, Brenda, Hsiao, Tiger Y.-Y, Mahler, Guillaume, Conselice, Christopher J, Broadhurst, Tom, Kokorev, Vasily, Bradač, Maruša

2023

Overview

We report the discovery of four galaxy candidates observed 450–600 Myr after the Big Bang with photometric redshifts between z ∼ 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 0.8–5.0 μm, plus nine Hubble Space Telescope filters spanning 0.4–1.7 μm. One candidate is gravitationally lensed with a magnification of μ ∼ 8, while the other three are located in a nearby NIRCam module with expected magnifications of μ ≲ 1.1. Using SED fitting, we estimate the stellar masses of these galaxies are typically in the range logM⋆/M⊙ = 8.3–8.7. All appear young, with mass-weighted ages <240 Myr, low dust content A V < 0.15 mag, and specific star formation rates sSFR ∼0.25–10 Gyr−1 for most. One z ∼ 9 candidate is consistent with an age <5 Myr and an sSFR ∼10 Gyr−1, as inferred from a strong F444W excess, implying [O iii ]+H β rest-frame equivalent width ∼2000 Å, although an older z ∼ 10 object is also allowed. Another z ∼ 9 candidate is lensed into an arc 2.″4 long with a magnification of μ ∼ 8. This arc is the most spatially resolved galaxy at z ∼ 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.

• Publisher: IOP Publishing
• Subject: Candidates / Dust content / Filters / Galactic clusters / Galaxies / Gravitational lenses / Hubble Space Telescope / James Webb Space Telescope / Physical properties / Red shift / Space telescopes / Spectroscopy / Star & galaxy formation / Star formation