The effect of bars and transient spirals on the vertical heating in disk galaxies

TL;DR

This study investigates how bars and transient spiral waves contribute to the vertical heating of stars in disk galaxies, using high-resolution N-body simulations to analyze their effects in different galactic regions.

Contribution

It demonstrates that galactic bars significantly influence vertical heating in the inner regions, and transient spirals affect outer disk heating, providing new insights into galaxy dynamics.

Findings

Bar growth rate correlates with vertical heating in the inner disk.

Transient spirals contribute to outer disk vertical heating.

Non-axisymmetric structures cause anisotropic stellar heating.

Abstract

The nature of vertical heating of disk stars in the inner as well as the outer region of disk galaxies is studied. The galactic bar (which is the strongest non-axisymmetric pattern in the disk) is shown to be a potential source of vertical heating of the disk stars in the inner region. Using a nearly self-consistent high-resolution N-body simulation of disk galaxies, the growth rate of the bar potential is found to be positively correlated with the vertical heating exponent in the inner region of galaxies. We also characterize the vertical heating in the outer region where the disk dynamics is often dominated by the presence of transient spiral waves and mild bending waves. Our simulation results suggest that the non-axisymmetric structures are capable of producing the anisotropic heating of the disk stars.