SCALING RELATIONS FOR THE TURBULENT, NON-SELF-GRAVITATING, NEUTRAL COMPONENT OF THE INTERSTELLAR MEDIUM

摘要

Scaling relations for the turbulent, non-self-gravitating, neutral component of the interstellar medium (ISM) are derived on the basis of von Weizsaecker's phenomenological model of compressible turbulence. The turbulent velocity v, column density N, gas density ρ, and mass M scale with region size l as v ～ N ～ ρ~(-1) ～ M~(1/5) ～ l~(1/2). In addition, the spectral energy function E(k) ～ k~(-2) for wavenumber k, and the diffuse cloud mass spectrum N(M) ～ M~(-2). These derived relations are shown to be in good agreement with observations. The scaling of magnetic field strength in these regions is briefly discussed, but uncertainties involved with compressible MHD turbulence preclude any definite predictions. It appears that turbulent hydrodynamics is the common underlying physics which controls many of the properties of the neutral component of the. ISM, independent of self-gravity.