Spherically symmetric models: Separating expansion from contraction in models with anisotropic pressures

José P. Mimoso (1, 2) , Morgan Le Delliou (2) , Filipe C. Mena (3)

1 DFUL - Departamento de Fı́sica, Faculdade de Ciências [University of Lisbon]
2 CAAUL - Centro de Astronomia e Astrofísica da Universidade de Lisboa
3 CMAT - Centro de Matemática [Minho]

We investigate spherically symmetric spacetimes with an anisotropic fluid and discuss the existence and stability of a dividing shell separating expanding and collapsing regions. We find that the dividing shell is defined by a relation between the pressure gradients, both isotropic and anisotropic, and the strength of the fields induced by the Misner-Sharpe mass inside the separating shell and by the pressure fluxes. This balance is a generalization of the Tolman-Oppenheimer-Volkoff equilibrium condition which defines a local equilibrium condition, but conveys also a non-local character given the definition of the Misner-Sharpe mass. We present a particular solution with dust and radiation that provides an illustration of our results.

Mots clés: astrophysical fluid dynamics; cosmology; space-time configurations; Spacetime topology; causal structure; spinor structure; Hydrodynamics; Particle-theory and field-theory models of the early Universe

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Physique des Hautes Energies - Théorie [hep-th]

José P. Mimoso, Morgan Le Delliou, Filipe C. Mena. Spherically symmetric models: Separating expansion from contraction in models with anisotropic pressures. SPANISH RELATIVITY MEETING 2011, Aug 2011, Madrid, Spain. pp.487-490, ⟨10.1063/1.4734466⟩. ⟨hal-00790345⟩