SPH Simulations of Spiral Galaxy Interarm Structure

Abstract

This work investigates the growth of substructures in spiral galaxies using Smoothed Particle Hydrodynamics(SPH) simulations. The impact of varying spiral arm potentials, gas temperatures and numerical resolutions onto interarm features, observed as feathering, is studied and compared to predictions made by the K-H instability model by Wada and Koda(2004) and the clump shearing model by Dobbs and Bonnell(2006). They are also compared to a recent Archival HST survey of Spiral Galaxy Feathering. The interarm featuresseen in SPH and relative pressure SPH(rpSPH) simulations, are found to be overall similar to observed feathers. High temperatures decreases velocity shear in the spiral arm shock regions and interarm structures are smoothed out entirely. Higher spiral arm potential strength increases velocity shear and the amount of interarm structures. While higher resolution is found to increase their visibility, the intrinsic interarm structures seem hardly affected. The effect of gas temperature and spiral arm potential strength variations onto gaseous interarm structure is found to be consistent with both theoretical models. An increase of interarm structure at low resolution as anticipatedin the clump shearing model is not observed.