The Star-forming Main Sequence and Bursty Star-formation Histories at z > 1.4 in JADES and AURORA

Abstract

We analyze JWST spectroscopic and Hubble Space Telescope+JWST photometric observations of 659 star-forming galaxies at 1.4 < z < 9 from DR3 of the JADES survey and the AURORA Cycle 1 program. We measure the star-forming main sequence (SFMS) for galaxies above 10 8.5 M ⊙ where the sample is largely representative, estimating star-formation rates (SFRs) using the H α line flux and rest-frame far UV (1600 Å) continuum measurements, each independently corrected for dust attenuation. We find that the intrinsic, measurement-error-subtracted scatter in the SFMS ( σ int ) increases with decreasing stellar mass for the H α -based SFMS, and we find no mass dependence of σ int in the UV-based SFMS. Additionally, we find that σ int decreases with increasing redshift, from 0.3 6 − 0.02 + 0.02 dex to 0.2 2 − 0.07 + 0.08 dex (H α SFMS), and from 0.2 8 − 0.02 + 0.02 dex to 0.2 0 − 0.07 + 0.08 dex (UV SFMS) between z ∼ 2 and z ∼ 6.5. We also measure the redshift evolution of the specific SFR and find that, assuming sSFR ∝ (1 + z) γ , γ = 1.8 9 − 0.15 + 0.16 for the H α -based SFMS, and γ = 1.3 6 − 0.13 + 0.13 for the UV-based SFMS. Analyzing the observed H α /UV luminosity ratios and star-formation histories from the prospector fitting code, we find that 41%–60% of the sample is inconsistent with having a constant star-formation history. Finally, we find tentative evidence for shorter SFR burst timescales with increasing redshift based on the distribution of L H α / ν L ν ,1600 versus Δ log ( L H α ) . Taken together, these results are consistent with recent theoretical predictions (e.g., the thesan-zoom simulations) of bursty star formation in the early Universe and provide valuable constraints for theoretical models of galaxy evolution.

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BibTeX RIS

BibTeX

@article{clarke2026starforming,
  title = {{The Star-forming Main Sequence and Bursty Star-formation Histories at z > 1.4 in JADES and AURORA}},
  author = {Leonardo Clarke and Alice E. Shapley and Natalie Lam and Michael W. Topping and Gabriel B. Brammer and Ryan L. Sanders and Naveen A. Reddy and Shreya Karthikeyan},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/ae9fec},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9fec},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - The Star-forming Main Sequence and Bursty Star-formation Histories at z > 1.4 in JADES and AURORA
AU  - Leonardo Clarke
AU  - Alice E. Shapley
AU  - Natalie Lam
AU  - Michael W. Topping
AU  - Gabriel B. Brammer
AU  - Ryan L. Sanders
AU  - Naveen A. Reddy
AU  - Shreya Karthikeyan
PY  - 2026
DA  - 2026/10/15
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae9fec
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/ae9fec
AB  - We analyze JWST spectroscopic and Hubble Space Telescope+JWST photometric observations of 659 star-forming galaxies at 1.4 < z < 9 from DR3 of the JADES survey and the AURORA Cycle 1 program. We measure the star-forming main sequence (SFMS) for galaxies above 10 8.5 M ⊙ where the sample is largely representative, estimating star-formation rates (SFRs) using the H α line flux and rest-frame far UV (1600 Å) continuum measurements, each independently corrected for dust attenuation. We find that the intrinsic, measurement-error-subtracted scatter in the SFMS ( σ int ) increases with decreasing stellar mass for the H α -based SFMS, and we find no mass dependence of σ int in the UV-based SFMS. Additionally, we find that σ int decreases with increasing redshift, from 0.3 6 − 0.02 + 0.02 dex to 0.2 2 − 0.07 + 0.08 dex (H α SFMS), and from 0.2 8 − 0.02 + 0.02 dex to 0.2 0 − 0.07 + 0.08 dex (UV SFMS) between z ∼ 2 and z ∼ 6.5. We also measure the redshift evolution of the specific SFR and find that, assuming sSFR ∝ (1 + z) γ , γ = 1.8 9 − 0.15 + 0.16 for the H α -based SFMS, and γ = 1.3 6 − 0.13 + 0.13 for the UV-based SFMS. Analyzing the observed H α /UV luminosity ratios and star-formation histories from the prospector fitting code, we find that 41%–60% of the sample is inconsistent with having a constant star-formation history. Finally, we find tentative evidence for shorter SFR burst timescales with increasing redshift based on the distribution of L H α / ν L ν ,1600 versus Δ log ( L H α ) . Taken together, these results are consistent with recent theoretical predictions (e.g., the thesan-zoom simulations) of bursty star formation in the early Universe and provide valuable constraints for theoretical models of galaxy evolution.
SN  - 0004-637X
SN  - 1538-4357
ER  -

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