Simulating the impact of the Smith Cloud

Abstract

We investigate the future evolution of the Smith Cloud by performing hydrodynamical simulations of the cloud impact onto the gaseous Milky Way Galactic disk. We assume a local origin for the cloud and thus do not include a dark matter component to stabilize it. Our main focus is the cloud's influence on the local and global star formation rate (SFR) of the Galaxy and whether or not it leads to an observable event in the far future. Our model assumes two extremes for the mass of the Smith Cloud, an upper mass limit of 10${}^7$ M${}_{\odot }$ and a lower mass limit of 10${}^6$ M${}_{\odot }$, compared to the observational value of a few 10${}^6$ M${}_{\odot }$. In addition, we also make the conservative assumption that the entirety of the cloud mass of the extended Smith Cloud is concentrated within the tip of the cloud. We find that the impact of the low-mass cloud produces no noticeable change in neither the global SFR nor the local SFR at the cloud impact site within the galactic disk. For the high-mass cloud we find a short-term (roughly 5 Myr) increase of the global SFR of up to 1 M${}_{\odot }$ yr${}^{-1}$, which nearly doubles the normal Milky Way SFR. This highly localized starburst should be observable.

14 pages, 5 figures

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• The Magellanic System: the puzzle of the leading gas stream
• The formation of young massive clusters by colliding flows
• The formation and early evolution of embedded star clusters in spiral galaxies
• The role of collision speed, cloud density, and turbulence in the formation of young massive clusters via cloud-cloud collisions
• Properties of 3D HI Filaments in the Smith High Velocity Cloud
• A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane
• Simulating High-Velocity Clouds in the Observational Plane: An Initial Study with the Smith Cloud