Living with Neighbors. VI. Unraveling the Dual Impact of Bars on Star Formation in Paired Galaxies Using DESI

TL;DR

This study investigates how stellar bars influence star formation in galaxy pairs, revealing that bars can either promote or suppress star formation depending on the companion galaxy’s activity, thus clarifying conflicting previous findings.

Contribution

It demonstrates the dual role of bars in galaxy pairs, showing their impact depends on the star-forming state of the companion galaxy, integrating internal and external factors.

Findings

Bars induce central starbursts with active companions.

Bars suppress star formation with passive companions.

The dual role explains conflicting previous reports.

Abstract

We present a comprehensive investigation into the influence of stellar bars on star formation (SF) in galaxy pairs, using a large sample of low-redshift galaxies ($0.02$\,$<$\,z\,$<$\,$0.08$) from the DESI Legacy Imaging Surveys DR8. Our analysis examines whether bars enhance or suppress SF during pair interactions, and how these outcomes depend on the star-forming properties of companion galaxies. We find that bars either catalyze or inhibit SF in their host galaxies, depending on the companion's SF activity. In particular, barred galaxies paired with actively star-forming companions experience more pronounced central starbursts (with sSFR up to $\sim$\,2.5 dex higher) than unbarred counterparts, whereas those with passive companions often have suppressed SF (sometimes below isolated galaxy levels). The notion of the dual role of bars can reconcile conventional conflicting reports of bar-driven enhancement versus quenching of SF activity. Bars, well known to regulate kpc-scale dynamics, may also link to the impact of external environments: when a star-forming companion provides sufficient gas, bars drive central starbursts, whereas in gas-poor interactions, bars hasten gas depletion and contribute to SF suppression. This work highlights the necessity of accounting for both internal structure and companion properties to fully understand SF regulation in interacting galaxies.