Title: Separating expansion and collapse in general fluids: local/non-local
conditions and spherically symmetric modelsAbstract: 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) |

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