Title: Separating expansion and collapse in general fluids: local/non-local conditions and spherically symmetric models
Abstract: Spherically symmetric spacetimes with perfect to general fluids shall be discussed with respect to the existence and stability of a dividing shell separating expanding and collapsing regions. The definition of the separating surface is inspired by the conservation of the Misner-Sharp mass and is obtained by generalizing the Tolman-Oppenheimer-Volkoff equilibrium and turnaround conditions. The equilibrium condition establishes a balance between the pressure gradients, both isotropic and anisotropic, and the strength of the fields induced by the Misner-Sharp mass inside the separating shell and by the pressure fluxes. General fluids with heat flux can be motivated by causal thermodynamics. We added the new requirement that heat flux and its evolution vanish at the separating surface. We have extended previous works with a fully nonlinear analysis in the 3 + 1 splitting and obtained gauge invariant conditions relating intrinsic spacetime quantities to properties of the matter source. Connections to the phenomena of spacetime cracking and thermal peeling are discussed.
Discussion Leader: Morgan Le Delliou (IFT-UNESP)