The pattern speeds of vertical breathing waves

TL;DR

This study measures and compares the pattern speeds of vertical breathing, bending, and spiral density waves in galaxy simulations, revealing that breathing motions are driven by and linked to spiral structures.

Contribution

It provides the first detailed comparison of pattern speeds of different wave modes in galaxy discs, showing breathing waves share pattern speeds with spirals and are driven by them.

Findings

Breathing waves have pattern speeds matching spiral density waves.

Bending waves exhibit different pattern speeds from breathing and spirals.

Breathing motions are driven by and integral to spiral structures.

Abstract

We measure and compare the pattern speeds of vertical breathing, vertical bending, and spiral density waves in two isolated N-body+SPH simulations, using windowed Fourier transforms over 1 Gyr time intervals. We show that the pattern speeds of the breathing waves match those of the spirals but are different from those of the bending waves. We also observe matching pattern speeds between the bar and breathing waves. Our results not only strengthen the case that, throughout the disc, breathing motions are driven by spirals but indeed that the breathing motions are part and parcel of the spirals.