Astrophysical Systems: A model based on the Self-similarity Scaling Postulates

Abstract

In the present work, it is developed a formalism to deal with the macroscopic study of the astrophysical systems, which is based on the consideration of the exponential self-similarity scaling laws that these systems exhibit during the realization of the thermodynamic limit. Due to their scaling laws, these systems are pseudoextensive, since although they are nonextensive in the usual sense, they can be studied by the Boltzmann-Gibbs Statistics if an appropriate representation of the integrals of motion of the macroscopic description is chosen. As example of application, it is analyzed the system of classical identical particles interacting via Newtonian interaction. A renormalization procedure is used in order to perform a well-defined macroscopic description of this system in quasi-stationary states, since it can not be in a real thermodynamic equilibrium. Our analysis showed that the astrophysical systems exhibit self-similarity under the following thermodynamic limit: $E\to \infty ,$ $L\to 0,$ $N\to \infty ,$ keeping $E/N^{7/3}=$const, $LN^{1/3}=$const, where $L$ is the characteristic linear dimension of the system. It is discussed the effect of these scaling laws in the dynamical properties of the system. In a general way, our solution exhibits the same features of the Antonov problem: the existence of the gravitational collapse at low energies as well as a region with a negative heat capacity.