Phase mixing in MOND

Abstract

Dissipationless collapses in Modified Newtonian Dynamics (MOND) have been studied by using our MOND particle-mesh N-body code, finding that the projected density profiles of the final virialized systems are well described by Sersic profiles with index m<4 (down to m~2 for a deep-MOND collapse). The simulations provided also strong evidence that phase mixing is much less effective in MOND than in Newtonian gravity. Here we describe "ad hoc" numerical simulations with the force angular components frozen to zero, thus producing radial collapses. Our previous findings are confirmed, indicating that possible differences in radial orbit instability under Newtonian and MOND gravity are not relevant in the present context.Comment: 10 pages, 3 figures. To appear in the Proceedings of the International Workshop "Collective Phenomena in Macroscopic Systems", G. Bertin, R. Pozzoli, M. Rome, and K.R. Sreenivasan, eds., World Scientific, Singapor