Evidence for Secular Evolution of Disc Structural Parameters in Massive Barred Galaxies

TL;DR

This study provides evidence that bars in massive disc galaxies influence their structural evolution, leading to fainter centers and larger disc scale lengths, supporting theories of bar-driven secular evolution.

Contribution

It offers the first large-scale statistical analysis showing how bars affect disc structural parameters, confirming theoretical predictions of secular evolution effects.

Findings

Barred discs have fainter central surface brightness than unbarred ones.

Barred discs exhibit ~15% larger scale lengths compared to unbarred discs.

Bars are rare in high-surface brightness discs, especially below 19.5 mag arcsec^-2.

Abstract

We address the effects of bar-driven secular evolution in discs by comparing their properties in a sample of nearly 700 unbarred and barred (42 +- 3 per cent of the population) massive disc galaxies (M* > 10^10 Msun). We make use of accurate structural parameters derived from i-band bulge/disc/bar decompositions to show that, as a population, barred discs tend to have fainter central surface brightness (Delta mu_0 ~ 0.25 mag), and disc scale lengths that are ~15 per cent larger than those of unbarred galaxies of the same stellar mass. The corresponding distributions of mu_0 and h are statistically inconsistent at the 5.2 sigma and 3.8 sigma levels, respectively. Bars rarely occur in high-surface brightness discs, with less than 5 per cent of the barred population having mu_0 < 19.5 mag arcsec^-2 -- compared to 20 per cent for unbarred galaxies. They tend to reside in moderately blue discs, with a bar fraction that peaks at (g-i)_disc ~ 0.95 mag and mildly declines for both bluer and redder colours. These results demonstrate noticeable structural differences between the discs of barred and unbarred galaxies, which we argue are the result of bar-driven evolution -- in qualitative agreement with longstanding theoretical expectations.