Statistical properties of classical gravitating particles in (2+1) dimensions

We report the statistical properties of classical particles in (2 + 1) gravity as resulting from numerical simulations. Only particle momenta have been taken into account. In the range of total momentum where thermal equilibrium is reached, the distribution function and the corresponding Boltzmann entropy are computed. In the presence of large gravity effects, different extensions of the temperature turn out to be inequivalent, the distribution function has a power law high-energy tail and the entropy as a function of the internal energy presents one inflection point. When the energy approaches the open universe limit, the entropy and the mean value of the particle kinetic energy seem to diverge. (C) 2001 Elsevier Science B.V. All rights reserved.