Probing the Faint Outskirts of Star-Forming Galaxies with 1<z<9 Using Stacked Images
Abstract
We present a systematic study of the faint outer light profiles of star-forming galaxies using deep JWST/NIRCam imaging from the CEERS, JADES, and PRIMER surveys. Our sample consists of 14,812 face-on disk galaxies at 1<z<9 with log(M*/M⊙)>8.5, selected from the DAWN JWST Archive. To characterize the low-surface-brightness outskirts beyond the effective radius (Re), we stack galaxies in bins of stellar mass and redshift, accounting for cosmological surface-brightness dimming, angular-size scaling, and PSF convolution, and estimate residual backgrounds from blank-sky stacks. The color profiles generally become bluer toward larger radii, indicating negative color gradients and supporting an inside-out growth scenario. Galaxies with log(M*/M⊙) < 9.5 at z>2.5 exhibit a weak reversal in their outermost regions, suggesting more complex stellar population gradients at early times. The outer light profiles generally exhibit a good exponential decline with radius, and the outer scale lengths measured beyond 2Re show mass and redshift dependences remarkably similar to those of the conventional mass-size relation. This similarity suggests that the extended outer light is closely linked to the same processes governing the growth of the inner galaxy, rather than providing a direct tracer of ex-situ stellar components in the early universe. We also find little wavelength dependence in the outer scale lengths, indicating that dust attenuation likely has a limited impact at these radii. These results provide new constraints on the buildup of extended stellar distributions during cosmic noon and at earlier epochs.
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BibTeX
@misc{jia2026probing,
title = {{Probing the Faint Outskirts of Star-Forming Galaxies with 1<z<9 Using Stacked Images}},
author = {Cheng Jia and Enci Wang and Yangyao Chen and Cheqiu Lyu and Hongxin Zhang and Ziwen Zhang and Jinyang Wang and Jie Song and Bojun Tao and Xiaoxuan Chen and Junsheng Li},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.04605},
eprint = {2611.04605},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.04605},
}
RIS
TY - UNPB
TI - Probing the Faint Outskirts of Star-Forming Galaxies with 1<z<9 Using Stacked Images
AU - Cheng Jia
AU - Enci Wang
AU - Yangyao Chen
AU - Cheqiu Lyu
AU - Hongxin Zhang
AU - Ziwen Zhang
AU - Jinyang Wang
AU - Jie Song
AU - Bojun Tao
AU - Xiaoxuan Chen
AU - Junsheng Li
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.04605
UR - https://arxiv.org/abs/2611.04605
AB - We present a systematic study of the faint outer light profiles of star-forming galaxies using deep JWST/NIRCam imaging from the CEERS, JADES, and PRIMER surveys. Our sample consists of 14,812 face-on disk galaxies at 1<z<9 with log(M_*/M_⊙)>8.5, selected from the DAWN JWST Archive. To characterize the low-surface-brightness outskirts beyond the effective radius (R_e), we stack galaxies in bins of stellar mass and redshift, accounting for cosmological surface-brightness dimming, angular-size scaling, and PSF convolution, and estimate residual backgrounds from blank-sky stacks. The color profiles generally become bluer toward larger radii, indicating negative color gradients and supporting an inside-out growth scenario. Galaxies with log(M_*/M_⊙) < 9.5 at z>2.5 exhibit a weak reversal in their outermost regions, suggesting more complex stellar population gradients at early times. The outer light profiles generally exhibit a good exponential decline with radius, and the outer scale lengths measured beyond 2R_e show mass and redshift dependences remarkably similar to those of the conventional mass-size relation. This similarity suggests that the extended outer light is closely linked to the same processes governing the growth of the inner galaxy, rather than providing a direct tracer of ex-situ stellar components in the early universe. We also find little wavelength dependence in the outer scale lengths, indicating that dust attenuation likely has a limited impact at these radii. These results provide new constraints on the buildup of extended stellar distributions during cosmic noon and at earlier epochs.
ER -