Investigating the Effects of Bars on Star Formation and Nuclear Activity of Galaxies Using DESI Survey Data

TL;DR

This study analyzes how galactic bars influence star formation and nuclear activity in disk galaxies, revealing that bars are linked to increased central star formation, higher AGN incidence, and galaxy evolution processes.

Contribution

It provides a comprehensive statistical analysis of the relationship between bars, star formation, and AGN activity using DESI survey data, highlighting the dual role of bars in galaxy evolution.

Findings

Strong bars are more common in massive, redder galaxies.

Barred galaxies show higher AGN activity, especially in strongly barred systems.

Bars influence central star formation differently in low-mass and high-mass galaxies.

Abstract

We present a statistical analysis of the connections between galactic bars, star formation, and active galactic nucleus (AGN) activity using 33,201 disk galaxies (0.01 < z < 0.05) from DESI DR1 cross-matched with Galaxy Zoo DESI. Based on morphological classifications, we identify 3,508 strongly barred and 8,335 weakly barred systems. We find that barred galaxies exhibit a clear bimodal distribution in color-mass space: weak bars are preferentially found in bluer, lower-mass disks, whereas strong bars are more common in massive, redder systems. Strongly barred galaxies are on average more massive and metal-rich than unbarred systems. In addition, strong bars enhance central SFRs in low-mass galaxies but reduce sSFRs in massive systems, reflecting a dual role where bars initially trigger central star formation but eventually promote quenching by accelerating gas consumption. In terms of nuclear activity, barred galaxies display a higher incidence of AGN activity. The presence of a bar is also associated with an increased fraction of powerful AGN, with the highest proportions found in strongly barred systems. However, the correlations between AGN activity and detailed bar structural parameters are weak, suggesting that the link between bars and nuclear activity is indirect and regulated by multiple factors. Overall, our results support a scenario in which bars facilitate angular-momentum transport and gas inflow, thereby driving central star formation and fueling supermassive black hole accretion while operating alongside other processes that shape galaxy evolution.