Statistical mechanics of the self-gravitating gases.

Julien Siebert (1)

1 LPTHE - Laboratoire de Physique Théorique et Hautes Energies

The self-gravitating systems are formed by particles interacting through gravity. They describe structure formation in the universe. As a consequence of the long range interaction of gravity, they are inhomogeneous even at thermal equilibrium. We study the self-gravitating systems with several kinds of particles and the self-gravitating systems in the presence of the cosmological constant $ Lambda$. We formulate the statistical mechanics and the mean field approach describing the gaseous phase. We explicitely compute the density of particles and thermodynamic quantities. The presence of $ Lambda$ extends the domain of stability of the gaseous phase. Monte Carlo simulations show that the mean field describes the gaseous phase with an excellent accuracy. Scalling law of the self-gravitating systems with several kinds of particles is found. At the critical point the fractal dimension is independant of their composition and is $1.6...$~.

Mots clés: GRAVITATION; COSMOLOGICAL CONSTANT; STRUCTURE FORMATION; MEAN FIELD; PHASE TRANSITION; MONTE CARLO COMPUTATION

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

Julien Siebert. Statistical mechanics of the self-gravitating gases.. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Pierre et Marie Curie - Paris VI, 2005. Français. ⟨NNT : ⟩. ⟨hal-00009142⟩