Gravity or turbulence? – III. Evidence of pure thermal Jeans fragmentation at ∼0.1 pc scale

We combine previously published interferometric and single-dish data of relatively nearby massive dense cores that are actively forming stars to test whether their 'frag- mentation level' is controlled by turbulent or thermal support. We find no clear correla- tion between the fragmentation level and velocity dispersion, nor between the observed number of fragments and the number of fragments expected when the gravitationally unstable mass is calculated including various prescriptions for 'turbulent support'. On the other hand, the best correlation is found for the case of pure thermal Jeans frag- mentation, for which we infer a core formation efficiency around 13%, consistent with previous works. We conclude that the dominant factor determining the fragmentation level of star-forming massive dense cores at 0.1 pc scale seems to be thermal Jeans fragmentation.