Drivers of the bending of the star-formation main sequence

Ascertain the physical mechanisms that drive the observed bending of the star-formation main sequence, both in integrated and spatially resolved forms, particularly at high stellar mass or stellar-mass surface density in disc galaxies.

Background

The star-formation main sequence (linking stellar mass and star-formation rate) exhibits a bending at high mass in both integrated and spatially resolved analyses. This feature is often attributed to bulge growth or central processes, but definitive causation is unsettled.

In this study, the spatially resolved analysis of six barred galaxies reveals an anti-correlation track within bar-hosting regions, suggesting that bars may contribute to inside-out quenching and potentially to the observed bending. However, the authors explicitly state that the exact mechanisms responsible for the bending remain unknown.

References

However, the precise drivers of this bending of the MS remain unknown.

— The impact of stellar bars on star-formation quenching: Insights from a spatially resolved analysis in the local Universe  (2404.11656 - Scaloni et al., 2024) in Section 5, Discussion

The reason for the slope deviation of the lowest-mass HSBG bin ([$\mathrm{M_{*}}$: 9.0 - 9.5; $\mathrm{\mu_{0}}$: 21.0 - 22.0]) remains unclear and requires further investigation.

— Inside-out growth and the kiloparsec-scale star formation main sequence for low-surface-brightness disk galaxies in MaNGA  (2609.02378 - Zhang et al., 2 Sep 2026) in Section 3.2, “Star formation main sequence, SFMS”