Swing amplification and global modes reciprocity in models with cusps

TL;DR

This paper investigates how swing amplification influences bar formation in cuspy galaxy models, showing that shot noise hampers but resonance perturbations facilitate bar growth, with simulation results aligning with global mode analysis.

Contribution

It reveals the dual role of swing amplification in bar formation in cuspy models, combining N-body simulations with global mode analysis.

Findings

Shot noise hampers bar formation due to disc discreteness.

Resonance perturbations enable bar amplitude to surpass shot noise.

Simulation results agree with global mode analysis.

Abstract

Using 3D N-body simulations we analyse an onset of the bar in cuspy models, and argue that role of swing amplification is twofold. Amplified shot noise due to disc discreteness hampers bar formation, while induced resonance perturbations allow bar amplitude to overcome shots. A bar pattern speed and a growth rate obtained in N-body simulations agree well with global mode analysis.