Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

TL;DR

This study analyzes 20 barred galaxies in the K_s-band, revealing that bars grow longer and stronger over cosmic time, especially in denser galaxies, indicating ongoing bar evolution over a Hubble time.

Contribution

It provides observational evidence that galactic bars increase in length and amplitude over time, correlating with galaxy density, supporting models of bar growth over a Hubble time.

Findings

Longer bars have higher m=2 Fourier amplitudes.

Bars are more prominent in denser galaxy centers.

Bar growth correlates with galaxy density and evolution.

Abstract

K_s-band images of 20 barred galaxies show an increase in the peak amplitude of the normalized m=2 Fourier component with the R_25-normalized radius at this peak. This implies that longer bars have higher $m=2$ amplitudes. The long bars also correlate with an increased density in the central parts of the disks, as measured by the luminosity inside 0.25R_25 divided by the cube of this radius in kpc. Because denser galaxies evolve faster, these correlations suggest that bars grow in length and amplitude over a Hubble time with the fastest evolution occurring in the densest galaxies. All but three of the sample have early-type flat bars; there is no clear correlation between the correlated quantities and the Hubble type.