EPoS Contribution
EPoS Contribution
Spectral energy density of interstellar turbulence

Alexei Kritsuk
UCSD, La Jolla, US
For over half-century, gravity, turbulence and magnetic fields were recognized as key players regulating star formation in molecular clouds, but the lack of a clear-cut physical concept of highly compressible magnetized turbulence was hindering our progress. In the past decade, the situation has noticeably improved on the theory front with new exact relations derived from the compressible Navier-Stokes equations, including the effects of magnetic field. In this contribution, we extend those earlier results to self-gravitating turbulence. This allows us, for the first time, to explore the physics of turbulent self-gravitating media in a comprehensive way with new rigorous statistical tools, measuring various energy exchange terms, spectral densities, and fluxes across the wide range of scales. We apply the new tools to data from AMR-MHD simulations with self-gravity to illustrate the co-existence of distinct physical regimes, e.g. weakly self-gravitating MHD turbulence (with magnetic-to-kinetic energy equipartition) on large scales, switching into weakly magnetized gravitoturbulence (with kinetic-to-gravitational energy equilibrium) on small scales. Unlike most traditional measures based on virial theorem, our statistics are conveniently defined in Fourier space and do not depend on contrived cloud concept. The spectral distributions of kinetic, magnetic, compressive and gravitational potential energy density across scales provide an unbiased picture of physical conditions in the turbulent star-forming ISM.
S. Banerjee, U Köln, DE
S. Galtier, U Paris-Süd, FR
D.C. Collins, FSU, US
Suggested Session: Turbulence