Probing the star formation main sequence down to 10 7 M ⊙ at 1 < z < 9
Year: 2026
Type: article
Abstract: The main sequence of star-forming galaxies (SFGMS or MS) is a fundamental scaling relation that provides a global framework for studying galaxy formation and evolution, as well as an insight into the complex star formation histories (SFHs) of individual galaxies. In this work, we combine large-area pre-JWST surveys (COSMOS2020, CANDELS), which probe high- M ★ sources (> 10 9 M ⊙ ), with SHARDS/CANDELS FAINT and JWST data from CANUCS, CEERS, JADES, and UNCOVER, to obtain a high- z , star formation rate (SFR) and stellar mass ( M ★ ) complete sample spanning both high- and low- M ★ regimes. Completeness in both M ★ and the SFR is key to avoiding biases introduced by low-mass, highly star-forming objects. Our combined dataset is 80% complete down to 10 7.6 M ⊙ at z ∼ 1 (10 8.8 M ⊙ at z ∼ 9). The overall intrinsic MS slope (based on the SFR 100 and M ★ derived with Dense Basis and nonparametric SFHs) shows little evolution up to z ∼ 5, with values ∼0.7 − 0.8. The slope in the low- M ★ regime becomes steeper than that in the high- M ★ end at least up to z ∼ 5, but the strength of this change is highly dependent on the assumptions made on the symmetry of the uncertainties in M ★ and SFR. If real, the steepening suggests reduced star formation efficiency or declining gas content with decreasing M ★ . The transition between the low- M ★ regime and the canonical MS occurs around 10 9.5 M ⊙ , independent of z . This critical value may coincide with the assembly of galaxies’ disks, which can provide a mechanism for self-regulation that stabilizes them against feedback. The intrinsic scatter is compatible with canonical estimates, also at low- M ★ , ranging from 0.2 − 0.3 dex. This is indicative of rapid variations in star formation being averaged out over ≲100 Myr.
Source: Astronomy and Astrophysics
Institutions: Saint Mary's University, Columbia University, Space Telescope Science Institute, Herzberg Institute of Astrophysics, National Research Council Canada, University of California, Davis, University of Groningen, York University, University of York, Universidad Nacional de Córdoba, Argentine National Observatory
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W4415331396