Zobrazeno 1 - 10
of 178
pro vyhledávání: '"Sáez, Juan Antonio"'
Publikováno v:
Class. Quantum Grav. 41 (2024) 205013
The necessary and sufficient conditions for a perfect fluid solution to define a spatially-homogeneous cosmology are achieved. These conditions are Intrinsic, Deductive, Explicit and ALgorithmic, and they offer an IDEAL labeling of these geometries.
Externí odkaz:
http://arxiv.org/abs/2409.15854
Publikováno v:
Phys. Rev. D 110, 044012 (2024)
The thermodynamic interpretation of the Stephani Universes is studied in detail. The general expression of the speed of sound and of the thermodynamic schemes associated with a thermodynamic solution is obtained. The constraints imposed on the soluti
Externí odkaz:
http://arxiv.org/abs/2409.01852
Publikováno v:
Class. Quantum Grav. 40 205020 (2023)
The necessary and sufficient conditions for a spacetime with an invariant frame to admit a group of isometries of dimension $r$ are given in terms of the connection tensor $H$ associated with this frame. In Petrov-Bel types I, II and III, and in othe
Externí odkaz:
http://arxiv.org/abs/2309.14100
Publikováno v:
Class.Quant.Grav. 40 (2023) 17, 175003
The necessary and sufficient conditions are obtained for a unit time-like vector field $u$ to be the unit velocity of a divergence-free perfect fluid energy tensor. This plainly kinematic description of a conservative perfect fluid requires consideri
Externí odkaz:
http://arxiv.org/abs/2309.00463
Publikováno v:
Phys. Rev. D 106 (2022) 124032
The necessary and sufficient conditions for a perfect energy tensor to describe the energy evolutions of a monoatomic relativistic Synge gas are obtained. Then, a Rainich-like theory for the Einstein-Synge solutions can be constructed. Equations of s
Externí odkaz:
http://arxiv.org/abs/2212.00591
The explicit expression of the multiple Debever null directions of an algebraically special spacetime are obtained in terms of the electric and magnetic parts of the Weyl tensor. An algorithm for the determination of the Petrov-Bel type and the algor
Externí odkaz:
http://arxiv.org/abs/2103.06158
Publikováno v:
Class. Quantum Grav. 38 (2021) 067001
The necessary and sufficient conditions for a three-dimensional Riemannian metric to admit a group of isometries of dimension $r$ acting on s-dimensional orbits are obtained. These conditions are Intrinsic, Deductive, Explicit and ALgorithmic and the
Externí odkaz:
http://arxiv.org/abs/2102.13358
Publikováno v:
Class. Quantum Grav. 37 (2020) 185005
In a recent paper (Coll {\em et al} 2019 {\it Class. Quantum Grav.} {\bf 36} 175004) we have studied a family of Szekeres-Szafron solutions of class II in local thermal equilibrium (singular models). In this paper we deal with a similar study for all
Externí odkaz:
http://arxiv.org/abs/2012.02317
Publikováno v:
Class. Quantum Grav. 37 (2020) 185011
The necessary and sufficient conditions for a three-dimensional Riemannian metric to admit a transitive group of isometries are obtained. These conditions are Intrinsic, Deductive, Explicit and ALgorithmic, and they offer an IDEAL labeling of these g
Externí odkaz:
http://arxiv.org/abs/2004.01877
Publikováno v:
Class. Quantum Grav. 36 (2019) 215008
he necessary and sufficient conditions for a unit time-like vector field to be the unit velocity of a classical ideal gas are obtained. In a recent paper [Coll, Ferrando and S\'aez, Phys. Rev D {\bf 99} (2019)] we have offered a purely hydrodynamic d
Externí odkaz:
http://arxiv.org/abs/1910.06791