Stellar population constraints on the ages of galactic bars

TL;DR

This study investigates the stellar populations in the central regions of four barred galaxies to determine the duration of bar activity, revealing that bars can be long-lived but with diverse stellar histories.

Contribution

It introduces a novel spectroscopic technique to constrain the duration of bar activity using stellar population analysis in galaxy centers.

Findings

Star formation suppression in the 'desert' regions has persisted for over 1 Gyr.

Two galaxies show star formation cessation lasting several Gyr.

Results support the idea that strong bars can be long-lived structures.

Abstract

We present a study of the stellar populations within the central regions of four nearby barred galaxies, and use a novel technique to constrain the duration of bar activity. We focus on the star formation 'desert', a region within each of these galaxies where star formation appears to have been suppressed by the bar. New H beta spectroscopic data are presented, and used to produce spectroscopic line indices which are compared with theoretical predictions from population synthesis models for simple stellar populations and temporally truncated star formation histories. This analysis shows that the dearth of star formation activity in these regions appears to have been continuing for at least 1 Gyr, with timescales of several Gyr indicated for two of the galaxies. This favours models in which strong bars can be long-lived features of galaxies, but our results also indicate a significant diversity in stellar population ages, and hence in the implied histories of bar activity in these four galaxies.