Spontaneous generation of bending waves in isolated Milky Way-like discs

Understand

We study the spontaneous generation and evolution of bending waves in $N$-body simulations of two isolated Milky Way-like galaxy models.

• The models differ by their disc-to-halo mass ratios, and hence by their susceptibility to the formation of a bar and spiral structure.
• Seeded from shot noise in the particle distribution, bending waves rapidly form in both models and persist for many billions of years.
• Waves at intermediate radii manifest as corrugated structures in vertical position and velocity that are tightly wound, morphologically leading, and dominated by the $m=1$ azimuthal Fourier component.