The Evolution of Bar Pattern Speed with Time and Bulge Prominence

TL;DR

This study analyzes nearly 300 galaxy bars to empirically test theoretical predictions, revealing correlations that suggest bars slow down and grow longer over time, especially in galaxies with prominent bulges.

Contribution

It provides observational evidence linking bar properties with galaxy evolution, supporting theories of bar slowdown and growth over cosmic time.

Findings

Bars with different ellipticities follow parallel correlations.

Bars grow longer and stronger as they slow down.

Pattern speeds decrease with time and bulge prominence.

Abstract

Results from the modelling of bars in nearly 300 galaxies are used to test predictions from theoretical work on the evolution of bars. Correlations are found between bar ellipticity and boxiness, between bar strength and normalised size, between the normalised sizes of bars and bulges, and between normalised bar size and bulge-to-total ratio. Bars with different ellipticities follow parallel lines in the latter two correlations. These correlations suggest that, formed with different sizes and ellipticities, bars slow down and grow longer and stronger, in agreement with theoretical work. As a consequence, bar pattern speeds should become lower with time, and towards galaxies with more prominent bulges.