Relative importance of star-formation-quenching pathways

Determine the relative importance of halo heating, environmental processes, stellar feedback, active galactic nucleus feedback, dynamical stabilization, morphological quenching, and angular-momentum-related suppression in causing the cessation of star formation in galaxies.

Background

The paper frames the cessation of star formation as a central problem in galaxy evolution and lists multiple possible mechanisms operating on different spatial scales. These include the removal, heating, or inhibited collapse of cold gas through halo shock heating, ram-pressure stripping, tidal effects, strangulation, mergers, stellar feedback, active galactic nucleus feedback, dynamical stabilization, morphological quenching, and angular-momentum-related suppression.

The study investigates how inferred associations between quenching and galaxy properties depend on the operational definition of quenched regions, but it does not resolve the broader physical question of which proposed pathways are most important. Its feature-importance analysis identifies statistical associations rather than causal mechanisms.

References

A central open question is whether gaseous outflows are a direct cause of quenching, or merely accompany a quenching process already underway.

— JWST Spectra Conclusively Show an Excess of Neutral Gas Outflows in Quiescent Galaxies at z=2-5  (2609.09459 - Oh et al., 8 Sep 2026) in Section 1, Introduction

Star formation can cease when cold gas is removed, heated, or prevented from collapsing efficiently, but the relative importance of these pathways remains debated.

— SDSS-IV MaNGA: Star Formation Cessation in Low-redshift Galaxies. III. Dependence on Quenching Criteria  (2608.24201 - Cheng et al., 25 Aug 2026) in Section 1, Introduction

Recent observations and simulations do suggest that AGN-driven outflows can affect dwarf or low-mass systems \citep[e.g.][]{Smethurst2016, Penny2018, Baldassare2020, Silk2017, Dashyan2018, Arjona2024, Salehirad2025}, but the role of such feedback remains uncertain.

— SDSS-IV MaNGA: Star Formation Cessation in Low-redshift Galaxies. III. Dependence on Quenching Criteria  (2608.24201 - Cheng et al., 25 Aug 2026) in Section 4.1, “Possible interpretations of $\Sigma_{\rm 1kpc}$”

However, due to our small sample statistics and the inability to directly detect outflows in our datasets, we cannot exclude the possibility that AGNs play only a marginal role in driving quenching. They may only become visible in galaxies that retain residual gas to accrete onto the central supermassive black hole, as in the case of ID 588, which has likely not yet reached complete quiescence. Thus, we cannot exclude the possibility that quenching is primarily driven by a strong phase of gas consumption, followed by starvation as a maintenance mechanism \citep[e.g.,][]{Croton06}. From these datasets, we cannot conclusively establish whether AGN feedback is crucial for inducing quenching in the Spiderweb protocluster.

— Rapid quenching and early gas depletion in the core of a galaxy protocluster at z=2.2  (2609.05285 - D'Eugenio et al., 4 Sep 2026) in Section 6.3, “The role of AGNs in driving quiescence”