The Effect of Bulge Mass on Bar Pattern Speed in Disk Galaxies

Abstract

We present a study of the effect of bulge mass on the evolution of bar pattern speed in isolated disk galaxies using N-body simulations. Earlier studies have shown that disk stars at the inner resonances can transfer a significant amount of angular momentum to the dark matter halo and this results in the slow down of the bar pattern speed. In this paper we investigate how the mass of the other spheroidal component, the bulge, affects bar pattern speeds. In our galaxy models the initial bars are all rotating fast as the R parameter, which is the ratio of the corotation radius to bar radius is less than 1.4, which is typical of fast bars. However, as the galaxies evolve with time, the bar pattern speed (${\Omega }_p$ ) slows down leading to R $>$1.4 for all the models except for the model with the most massive bulge, in which the bar formed late and did not have time to evolve. The rapid slowdown of ${\Omega }_p$ is due to the larger angular momentum transfer from the disk to the bulge, and is due to interactions between stars at the inner resonances and those in the bar. Hence we conclude that the decrease in ${\Omega }_p$ clearly depends on bulge mass in barred galaxies and decreases faster for galaxies with more massive bulges. We discuss the implications of our results for observations of bar pattern speeds in galaxies.

12 Pages, 12 Figures, 4 Tables,Accepted in ApJ

References in corpus (7)

• Properties of Bars and Bulges in the Hubble Sequence
• Model-based pattern speed estimates for 38 barred galaxies
• Fourier Dissection of Early-Type Galaxy Bars
• A Study of the Effect of Bulges on Bar Formation in Disk galaxies
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• Effects of the Central Mass Concentration on Bar Formation in Disk Galaxies
• The Effect of Dark Matter Halo Shape on Bar Buckling and Boxy/Peanut Bulges
• A new resonance-like feature in the outer disc of the Milky Way
• Testing a theoretical prediction for bar formation in galaxies with bulges
• Modelling Dark Matter Halo Spin using Observations and Simulations: application to UGC 5288
• Growth of disc-like pseudo-bulges in SDSS DR7 since z = 0.1
• The role of impact parameter in typical close galaxy flybys
• Bar instability and formation timescale across Toomre's $Q$ parameter and central mass concentration: slow bar formation or true stability
• Dynamical analysis of Maclaurin disk with velocity dispersion and its influence on bar formation
• Morphological evolution of disk galaxies and their concentration, asymmetry and clumpiness (CAS) properties in simulations across Toomre's $Q$ parameter