Two Remarkably Luminous Galaxy Candidates at $z\approx10-12$ Revealed by JWST

Abstract

The first few hundred Myrs at z > 10 mark the last major uncharted epoch in the history of the Universe, where only a single galaxy (GNz11 at z ≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z > 10 galaxies with JWST /NIRCam photometry spanning ≈ 1 − 5µm and covering 49 arcmin 2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two M UV ≈ −21 systems: GLASS-z13 and GLASS-z11. These galaxies display abrupt 2.5 mag breaks in their spectral energy distributions, consistent with complete absorption of flux bluewards of Lyman-α that is redshifted to z ≈ 13 and z ≈ 11. Lower redshift interlopers such as dusty quiescent galaxies with strong Balmer breaks would be comfortably detected at > 5σ in multiple bands where instead we find no flux. From SED modeling we infer that these galaxies have already built up ∼ 10 9 solar masses in stars over the 300−400 Myrs after the Big Bang. The brightness of these sources enable morphological constraints. Tantalizingly, GLASS-z11 shows a clearly extended exponential light profile, potentially consistent with a disk galaxy of r 50 ≈ 0.7 kpc. These sources, if confirmed, join GNz11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area > 10× larger than we have studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn

The evolution of the galaxy UV luminosity function at redshifts z ~ 8-15 from deep JWST and ground-based near-infrared imaging

“…There are 39 galaxies in the final high-redshift (𝑧 > 8.5) sample uncovered by our analysis of the ERO/ERS JWST NIRCam imaging, with 16 found in SMACS0723, 21 in CEERS, and only 2 in GLASS. Both of the high-redshift galaxies we have found here in the GLASS field have been independently discovered by Naidu et al (2022) and Castellano et al (2022), namely GLASS-1698 and GLASS-17487 in our sample which we find to lie at 𝑧 = 10.56 and 𝑧 = 12.42 respectively (consistent with the independently reported photometric redshifts). We fail to recover robust high-redshift solutions for any of the five sources that Castellano et al (2022) reported in their fainter sample.…”

Revealing Galaxy Candidates out to $z \sim 16$ with JWST Observations of the Lensing Cluster SMACS0723

“…We measured 𝑛 = 1.1 ± 0.2 for SMACS_z16a, which corresponds to disk-like profile. Such a morphology was also observed for GLz13 (Naidu et al 2022), as well as in several other high-redshift candidates reported in Adams et al (2022). The existence of well settled disks at early epochs will provide strong constraints on theoretical models of galaxy formation.…”

“…While some of our sources are relatively bright, they all have luminosities around, or below, the characteristic luminosity 𝑀 ★ at 𝑧 ∼ 9 − 10 (Oesch et al 2018;Bouwens et al 2021). The highest redshift candidate in our sample, SMACS_z16, has an intrinsic UV magnitude of 𝑀 UV = −21.23 ± 0.27, which is fainter than previous the very high redshift candidates Gn_z11 and HD1, and slightly brighter than the recently discovered candidate GLz13 (Naidu et al 2022). Moreover, the yield of the galaxy hunt presented in this paper is surprisingly high, with the discovery of 2 candidates at 𝑧 ∼ 16, 2 candidates at 𝑧 ∼ 12, and 11 candidates at 𝑧 = 10 − 11.…”

“…This source is also among the highest-redshift candidates identified photometrically in the literature (e.g. Harikane et al 2022;Naidu et al 2022;Castellano et al 2022), around 360 Myr after the Big Bang. The derived are very similar to SMACS_z16a, with a stellar mass of log(𝑀 ★ /M ) = 8.18 +0.64 −0.33 , and an age of log(𝑡 age /yr) = 7.64 +0.41 −0.39 .…”

“…The candidates in this work are shown as orange filled hexagons, while empty hexagon marks the less secure candidate. The empty purple pentagons show the recently identified candidates from JWST in the GLASS parallel field by Naidu et al (2022). The empty blue circles show photometric redshift galaxies while the solid circles represent spectroscopically confirmed galaxies compiled from Bouwens et al (2022).…”