Shock-Turbulence Interactions in Star Formation

Abstract

Multiscale processes in the interstellar medium (ISM) can be modeled as shocks encountering turbulent gas. Much of the gas in the ISM is characterized by supersonic turbulence, which produces a chaotic network of shocks. These shocks collide frequently, creating vortices and smaller-scale shocks that serve to dissipate energy. This energy cascade, from large to small scales, is crucial for regulating the rate of star formation. Recent studies of the local solar neighborhood have also underscored the significant role of supernovae and other stellar feedback processes in this regard. Feedback-produced shocks propagate into the turbulent ISM, driving compressive motions that may initiate gravitational gas collapse into molecular clouds. Remarkably, nearly all of the molecular clouds in the local solar neighborhood lie on the surfaces of feedback-driven shells expanding into the ambient turbulent ISM. Within these molecular clouds, supersonic turbulence continues to foster the formation of dense regions that can eventually collapse to form stars. Despite the importance of "shock-turbulence" interactions across multiple scales of the star formation process, their hydrodynamics remain poorly constrained in astrophysical contexts. This thesis supports the burgeoning investigation of astrophysical shock-turbulence interactions through both a large hydrodynamical simulation suite and an observational case study in the Orion star-forming region. Given the challenges of modeling the chaotic nature of turbulence analytically, the results underscore the importance of broader parameter studies of isolated shock-turbulence interactions. By integrating simulations with recent observational advances in 3D mapping techniques for the ISM, this thesis highlights the exciting prospect of connecting the physics of shock-turbulence interactions with open questions in star formation.