Dancing Streams in Merging Halos: Effects of Major Mergers on Stellar Streams

Stellar streams orbiting a galaxy are great probes of that galaxy’s history. Streams exist of stars which together once formed a smaller system, a globular cluster or dwarf galaxy, that has been torn apart by tidal forces. Stellar streams may be used to constrain halo masses and detect dark-matter sub structures, or learn about smaller-mass systems and the formation history of the host galaxy. Previous studies have looked at the effects of the Large Magellanic Cloud (LMC) on stellar streams in the Milky Way. However, a complete sense of the impact of halo mergers on stellar streams remains unexplored. We run a suite of N-body simulations with streams around a Milky Way like halo during a major merger event with satellites with varying halo masses, and study the stream evolution during major and minor mergers. We characterize the differences in morphology, structure, and survival of streams during a galaxy interactions, and identify possible dependencies of their evolution on orbital properties, location, and ages. We find that streams can be significantly affected by mergers, and our results thus open up opportunities to study past mergers through stellar streams.