A Large Scale Energy Source For Feeding ISM Turbulence in Spiral Galaxies

One of the important consequences of a newly discovered secular dynamical evolution process of spiral galaxies (Zhang 1996,1998,1999) is that the orbiting disk matter receives energy injection each time it crosses the spiral density wave crest. This energy injection has been shown to be able to quantitatively explain the observed age-velocity-dispersion relation of the solar neighborhood stars. We demostrate in this paper that similar energy injection into the interstellar medium could serve as the large-scale energy source to continuously power the observed interstellar turbulence and to offset its downward cascade tendency.