The impact of gas inflows on star formation rates and metallicities in barred galaxies

TL;DR

This study compares star formation rates and metallicities in barred and unbarred galaxies, finding that bars influence central metallicity and star formation, with bars contributing more to triggered star formation than galaxy interactions.

Contribution

It provides the first detailed comparison of star formation and metallicity differences between barred and unbarred galaxies, quantifying the impact of bars versus interactions.

Findings

Barred galaxies have higher central metallicities than unbarred ones.

Star formation rates are significantly higher in high-mass barred galaxies.

Bars contribute approximately 3.5 times more to triggered central star formation than galaxy pairs.

Abstract

The star formation rates (SFRs) and metallicities of a sample of 294 galaxies with visually classified, strong, large-scale bars are compared to a control sample of unbarred disk galaxies selected from the Sloan Digital Sky Survey Data Release 4. The fibre (inner few kpc) metallicities of barred galaxies are uniformly higher (at a given mass) than the unbarred sample by ~0.06 dex. However, the fibre SFRs of the visually classified barred galaxies are higher by about 60% only in the galaxies with total stellar mass log M > 10. The metal enhancement at log M<10 without an accompanying increase in the SFR may be due to a short-lived phase of early bar-triggered star formation in the past, compared to on-going star formation rate enhancements in higher mass barred galaxies. There is no correlation between bar length or bar axial ratio with the enhancement of the star formation rate. In order to assess the relative importance of star formation triggered by bars and galaxy-galaxy interactions, SFRs are also determined for a sample of close galaxy pairs. Both mechanisms appear to be similarly effective at triggering central star formation for galaxies with log M>10. However, due to the much lower fraction of pairs than bars, bars account for ~3.5 times more triggered central star formation than interactions.