What shapes the bright end of the UV luminosity function? Stellar mass, star-formation variability, and dust in JADES
Abstract
JWST surveys find more UV-bright galaxies at z>10 than galaxy-formation models predict, but the roles of recent star formation, stellar mass and dust remain uncertain. We analyse 1365 spectroscopically confirmed JADES galaxies at 3≤ z≤9, fitting NIRCam photometry and NIRSpec emission lines with \ceri. Our model includes flexible star-formation histories (SFHs) under three priors, two-component dust attenuation and nebular emission. We account for spectroscopic selection through population reweighting and assess the reliability of inferred trends. At z=3--5, rising SFHs are more common in low-mass galaxies, whereas most galaxies above 109.5 M⊙ have declining SFHs. The apparent increase in rising fractions with redshift cannot be distinguished from the adopted SFH prior alone. At fixed stellar mass, recent star formation is the strongest predictor of UV brightness. UV-brighter galaxies have higher recent SFRs, younger stellar populations and less attenuation at fixed SFR. Below 109 M⊙, they are also more likely to have rising SFHs, with odds increasing by up to a factor of 2.3 per magnitude brighter, although the strongest trend requires caution. In contrast, galaxies with MUV<−20 at z=3--5 are predominantly massive, and approximately half have declining SFHs. Dust partly offsets burst-driven UV brightening: attenuation increases with recent SFR and declines gradually after the inferred SFR peak. In model sensitivity tests, dust has the largest effect on bright-end counts, whereas removing galaxy-to-galaxy SFH scatter changes them by at most 0.17~dex. Thus, bursts can make low-mass galaxies unusually UV-bright for their mass, while the absolute bright end of the UVLF is primarily shaped by stellar mass and dust attenuation.
Related
- The JWST Emission Line Survey (JELS): A narrow-band determination of the Hα Luminosity Function and Cosmic Star Formation into the Epoch of Reionization
- Stellar masses and ages in Gaia Data Release 4 from the Final Luminosity Age Mass Estimator algorithm
- Radiation Pressure Instability-Driven Variability of Line-Driven Disk Winds in AGNs: Connection to Periodic Luminosity Variations and UFO Appearance
- Photometric variability of blue supergiants: Constraints on stellar masses and evolutionary stages
- Dual Signatures of Bursty Star Formation in High-Redshift UV Luminosity Functions
BibTeX
@misc{stoffers2026what,
title = {{What shapes the bright end of the UV luminosity function? Stellar mass, star-formation variability, and dust in JADES}},
author = {Amanda Stoffers and Sandro Tacchella and Benjamin D. Johnson and Brant Robertson and Roberto Maiolino and Andrew J. Bunker and Emma Curtis-Lake and A. Lola Danhaive and Qiao Duan and Francesco D'Eugenio},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37643},
eprint = {2610.37643},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37643},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - What shapes the bright end of the UV luminosity function? Stellar mass, star-formation variability, and dust in JADES
AU - Amanda Stoffers
AU - Sandro Tacchella
AU - Benjamin D. Johnson
AU - Brant Robertson
AU - Roberto Maiolino
AU - Andrew J. Bunker
AU - Emma Curtis-Lake
AU - A. Lola Danhaive
AU - Qiao Duan
AU - Francesco D'Eugenio
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37643
UR - https://arxiv.org/abs/2610.37643
AB - JWST surveys find more UV-bright galaxies at z>10 than galaxy-formation models predict, but the roles of recent star formation, stellar mass and dust remain uncertain. We analyse 1365 spectroscopically confirmed JADES galaxies at 3≤ z≤9, fitting NIRCam photometry and NIRSpec emission lines with \ceri. Our model includes flexible star-formation histories (SFHs) under three priors, two-component dust attenuation and nebular emission. We account for spectroscopic selection through population reweighting and assess the reliability of inferred trends. At z=3--5, rising SFHs are more common in low-mass galaxies, whereas most galaxies above 10^9.5 M_⊙ have declining SFHs. The apparent increase in rising fractions with redshift cannot be distinguished from the adopted SFH prior alone. At fixed stellar mass, recent star formation is the strongest predictor of UV brightness. UV-brighter galaxies have higher recent SFRs, younger stellar populations and less attenuation at fixed SFR. Below 10^9 M_⊙, they are also more likely to have rising SFHs, with odds increasing by up to a factor of 2.3 per magnitude brighter, although the strongest trend requires caution. In contrast, galaxies with M_UV<−20 at z=3--5 are predominantly massive, and approximately half have declining SFHs. Dust partly offsets burst-driven UV brightening: attenuation increases with recent SFR and declines gradually after the inferred SFR peak. In model sensitivity tests, dust has the largest effect on bright-end counts, whereas removing galaxy-to-galaxy SFH scatter changes them by at most 0.17~dex. Thus, bursts can make low-mass galaxies unusually UV-bright for their mass, while the absolute bright end of the UVLF is primarily shaped by stellar mass and dust attenuation.
ER -