Density structure and intermittency in decaying supersonic interstellar turbulence: Kolmogorov versus Burgers scales

Abstract

Abstract We investigate how the initial spectral organization of decaying supersonic turbulence influences the structure and intermittency of the interstellar medium. Three-dimensional isothermal Euler simulations are performed at identical initial turbulent Mach number for Kolmogorov-type, E(k) ∼ k −5/3, and Burgers-type, E(k) ∼ k −2, velocity fields using the high-order finite-volume PLUTO [16] framework. Here, these terms denote prescribed initial spectral organizations and do not imply that spectral slope uniquely determines solenoidal or compressive mode content. The two states are idealized initial conditions rather than complete models of specific interstellar environments or driving mechanisms. Without external forcing or self-gravity, the Burgers-type realization exhibits broader density distributions, stronger helicity localization in overdense regions, and more intermittent turbulent kinetic-energy fluctuations. At the representative diagnostic time, these differences show that the initial spectral organization leaves a measurable imprint on the nonlinear state. The conclusions are restricted to freely decaying, isothermal, non-self-gravitating supersonic turbulence and do not establish gravitational boundedness, collapse, or a specific star-formation mechanism.