What becomes of JWST/NIRCam-selected high-redshift massive galaxies?
Abstract
Early JWST/NIRCam surveys revealed a puzzling population of high-redshift massive galaxy candidates largely absent from previous rest-frame UV surveys. Spectroscopic follow-up has both confirmed and contested these candidates, whose potential overabundance may challenge traditional models of galaxy formation. In this study we evaluate the reliability of the photometric selections used to identify these candidates in observational data by applying them to galaxies in the TNG300 simulation with synthetic dust-attenuated photometry. Among the five observational selection criteria considered, we find that the selection presented by Pérez-González et al. is the most reliable and inclusive. Nevertheless, only 1 of the 18 galaxies at z∼5 with M⋆ ≥ 1011 M⊙ in the simulation satisfies this selection; the remaining 17 galaxies are on average ∼0.5 mag bluer than the color selection under the adopted dust model. We construct an improved JWST/NIRCam color-magnitude selection that provides a more complete census of massive galaxies at z∼5 in TNG300 while excluding dusty, low-mass galaxies identified by criteria from the observational literature. We investigate the descendants of the most massive NIRCam-selected galaxies at z=7, 4, and $2$ in TNG300, finding that they rarely evolve into the most massive galaxies by z=0. In general only the high-redshift massive galaxies that undergo substantial late-time (z≲0.2) merger-driven growth become the most massive galaxies in the Universe today. Together these results suggest that current observational JWST/NIRCam selections are not identifying the most massive high-redshift galaxies, and caution against interpreting high-redshift massive galaxies as direct progenitors of the most massive galaxies at z=0.
Related
- PANORAMIC: The Dawn of Massive Quiescent Galaxies. I. Number Density and Cosmic Variance from 1000 arcmin ² NIRCam Imaging
- EPOCHS-DR2 I: Expanded data release and properties of 6.5<z<16.5 photometrically selected galaxies across NIRCam deep fields covering ∼700 arcmin2 with the galfind software
- DeepDive: Simultaneous Formation of Massive Quiescent Galaxies in High-redshift Galaxy Overdensities
- Rest-Frame UV and Optical Structural Evolution of Narrowband-Selected Lyman-alpha Emitters at z = 2-7 with JWST/NIRCam
- Probing Direct Contributions of Galaxies and AGN to Cosmic Reionization in a Quasar Field J0226+0302 with JWST NIRCam and NIRSpec
BibTeX
@misc{baxter2026what,
title = {{What becomes of JWST/NIRCam-selected high-redshift massive galaxies?}},
author = {Devontae C. Baxter and Alison L. Coil and Ethan O Nadler and Xuejian Shen and Mark Vogelsberger},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.08820},
eprint = {2607.08820},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.08820},
}
RIS
TY - UNPB
TI - What becomes of JWST/NIRCam-selected high-redshift massive galaxies?
AU - Devontae C. Baxter
AU - Alison L. Coil
AU - Ethan O Nadler
AU - Xuejian Shen
AU - Mark Vogelsberger
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2607.08820
UR - https://arxiv.org/abs/2607.08820
AB - Early JWST/NIRCam surveys revealed a puzzling population of high-redshift massive galaxy candidates largely absent from previous rest-frame UV surveys. Spectroscopic follow-up has both confirmed and contested these candidates, whose potential overabundance may challenge traditional models of galaxy formation. In this study we evaluate the reliability of the photometric selections used to identify these candidates in observational data by applying them to galaxies in the TNG300 simulation with synthetic dust-attenuated photometry. Among the five observational selection criteria considered, we find that the selection presented by Pérez-González et al. is the most reliable and inclusive. Nevertheless, only 1 of the 18 galaxies at z∼5 with M_⋆ ≥ 10^11 M_⊙ in the simulation satisfies this selection; the remaining 17 galaxies are on average ∼0.5 mag bluer than the color selection under the adopted dust model. We construct an improved JWST/NIRCam color-magnitude selection that provides a more complete census of massive galaxies at z∼5 in TNG300 while excluding dusty, low-mass galaxies identified by criteria from the observational literature. We investigate the descendants of the most massive NIRCam-selected galaxies at z=7, 4, and $2$ in TNG300, finding that they rarely evolve into the most massive galaxies by z=0. In general only the high-redshift massive galaxies that undergo substantial late-time (z≲0.2) merger-driven growth become the most massive galaxies in the Universe today. Together these results suggest that current observational JWST/NIRCam selections are not identifying the most massive high-redshift galaxies, and caution against interpreting high-redshift massive galaxies as direct progenitors of the most massive galaxies at z=0.
ER -