27 citations · 123 across the 14 of their papers we have counts for
14 papers
Thermodynamics of the universes admitting isotropic radiation
Salvador Mengual, Joan Josep Ferrando, Juan Antonio Sáez
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 the…
On the flow of perfect energy tensors
Juan Antonio Sáez, Salvador Mengual, Joan Josep Ferrando
The necessary and sufficient conditions are obtained for a unit time-like vector field to be the unit velocity of a divergence-free perfect fluid energy tensor. This plainly ki…
Relativistic perfect fluids in local thermal equilibrium
Bartolomé Coll, Joan Josep Ferrando, Juan Antonio Sáez
Every evolution of a fluid is uniquely described by an energy tensor. But the converse is not true: an energy tensor may describe the evolution of different fluids. The problem of…
Null conformal Killing-Yano tensors and Birkhoff theorem
Joan Josep Ferrando, Juan Antonio Sáez
We study the space-times admitting a null conformal Killing-Yano tensor whose divergence defines a Killing vector. We analyze the similitudes and differences with the recently stud…
Birkhoff theorem and conformal Killing-Yano tensors
Joan Josep Ferrando, Juan Antonio Sáez
We analyze the main geometric conditions imposed by the hypothesis of the Jebsen-Birkhoff theorem. We show that the result (existence of an additional Killing vector) does not nece…
Type D vacuum solutions: a new intrinsic approach
Joan Josep Ferrando, Juan Antonio Sáez
We present a new approach to the intrinsic properties of the type D vacuum solutions based on the invariant symmetries that these spacetimes admit. By using tensorial formalism and…