We investigate the influence of the turbulence forcing on the massdistributions of gravitationally unstable cores by postprocessing data fromsimulations of non-selfgravitating isothermal supersonic turbulence withvarying resolution. In one set of simulations solenoidal forcing is applied,while the second set uses purely compressive forcing to excite turbulentmotions. From the resulting density field, we compute the mass distribution ofgravitationally unstable cores by means of a clump-finding algorithm. Using thetime-averaged probability density functions of the mass density, semi-analyticmass distributions are calculated from analytical theories. We apply stabilitycriteria that are based on the Bonnor-Ebert mass resulting from the thermalpressure and from the sum of thermal and turbulent pressure. Although there areuncertainties in the application of the clump-finding algorithm, we findsystematic differences in the mass distributions obtained from solenoidal andcompressive forcing. Compressive forcing produces a shallower slope in thehigh-mass power-law regime compared to solenoidal forcing. The massdistributions also depend on the Jeans length resulting from the choice of themass in the computational box, which is freely scalable for non-selfgravitatingisothermal turbulence. Provided that all cores are numerically resolved andmost cores are small compared to the length scale of the forcing, thenormalised core mass distributions are found to be close to the semi-analyticmodels. Especially for the high-mass tails, the Hennebelle-Chabrier theoryimplies that the additional support due to turbulent pressure is important.
展开▼
