Violent Buckling Benefits Galactic Bars

TL;DR

This paper models the vertical buckling instability in galactic bars using classical Euler buckling theory and nonlinear damping, showing that violent buckling preserves bars while gentle buckling can dissolve them, explaining observed bar fractions.

Contribution

It introduces a new analytical framework for understanding galactic bar buckling, linking classical mechanics with astrophysical simulations to explain bar stability outcomes.

Findings

Violent buckling does not destroy galactic bars.

Gentle buckling can lead to bar dissolution.

Results align with recent observational surveys.

Abstract

Galactic bars are unstable to a vertical buckling instability which heats the disk and in some cases forms a boxy/peanut shaped bulge. We analyze the buckling instability as an application of classical Euler buckling followed by nonlinear gravitational Landau damping in the collisionless system. We find that the buckling instability is dictated by the kinematic properties and geometry of the bar. The analytical result is compared to simulations of isolated galaxies containing the disk and dark matter components. Our results demonstrate that violent buckling does not destroy bars while a less energetic buckling can dissolve the bar. The disks that undergo gentle buckling remain stable to bar formation which may explain the observed bar fraction in the local universe. Our results align with the results from recent surveys.