Cloud Crushing and Dissipation of Uniformly Driven Adiabatic Turbulence in Circumgalactic Media

Abstract The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252 numerical simulations with proper cooling mechanisms and a large parameter space spanning average gas density, metallicity, and turbulence driving strength. A dichotomy emerges in the dynamics dissipation behaviors upon turbulence driving turnoff. Hot and subsonic disturbances are characterized by weak compression and slow dissipation, while warm and supersonic turbulences are marked by significant compression shocks and subsequent rapid cooling. In the supersonic cases, the kinetic energy decay is divided into a rate-limiting phase of shock dissipation and a comparatively swift phase of thermal dissipation, predominantly occurring within the overdense regions. Dense clouds are crushed on relatively brief timescales of ∼30–100 Myr, depending on turbulence driving strength but independent from average gas density. This independence is in spite of the complex interplay between the kinetics and thermodynamics of dissipation. The brevity of such timescales relative to typical dynamical timescales within the CGM suggests turbulent clouds must be cotemporal with turbulence driving sources such as cool accretion flows or feedback from the interstellar medium. Quantitative results from this work contribute a novel data set of dissipation timescales that incorporates thermodynamics and radiative cooling in an area of study typically focused on kinematics, which may serve as a valuable asset for forthcoming simulations that aim to explore gas dynamics on galactic and cosmological scales.