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pro vyhledávání: '"Bergh, Norbert Van den"'
Autor:
Bergh, Norbert Van den
The present status of the shear-free perfect fluid conjecture in general relativity is discussed: I give a review of recent work and present a new formalism which may provide a better understanding of the problems encountered.
Comment: 27 pages;
Comment: 27 pages;
Externí odkaz:
http://arxiv.org/abs/2309.10478
We point out an error in a recent paper by Goswami and Ellis. As a consequence the question of whether shear-free barotropic perfect fluids (with $p+\mu\neq 0$) can or cannot rotate and expand simultaneously, is still wide open
Comment: 3 pages
Comment: 3 pages
Externí odkaz:
http://arxiv.org/abs/2111.06303
We discuss Petrov type D Einstein-Maxwell fields in which both double null eigenvectors of the Weyl tensor are non-aligned with the eigenvectors of a non-null electromagnetic field and are assumed to be geodesic, shear-free, diverging and non-twistin
Externí odkaz:
http://arxiv.org/abs/2009.11516
Autor:
Bergh, Norbert Van den
In a recent study [NVdB2017] of algebraically special Einstein-Maxwell fields it was shown that, for non-zero cosmological constant, non-aligned solutions cannot have a geodesic and shearfree multiple Debever-Penrose vector k. When $\Lambda=0$ such s
Externí odkaz:
http://arxiv.org/abs/1806.09950
Autor:
Bergh, Norbert Van den
Publikováno v:
Phys. Rev. D 96, 104056 (2017)
Rotating and twisting locally rotationally symmetric imperfect fluids in general relativity admit a much larger set of solutions than the self-similar ones recently suggested in the literature. Explicit forms of the metrics are given and the self-sim
Externí odkaz:
http://arxiv.org/abs/1710.06179
Autor:
Bergh, Norbert Van den
The Geroch-Held-Penrose formalism is used to re-analyse algebraically special non-null Einstein-Maxwell fields, aligned as well as non-aligned, in the presence of a possible non-vanishing cosmological constant. A new invariant characterisation is giv
Externí odkaz:
http://arxiv.org/abs/1605.05830
The present status of the shear-free fluid conjecture in general relativity is discussed: a review is given of recent partial proofs, a new and complete proof is given for the case of a linear equation of state, including a non-zero cosmological cons
Externí odkaz:
http://arxiv.org/abs/1510.05798
Autor:
Bergh, Norbert Van den
I present a complete list of hypersurface homogeneous space-times admitting a non-null valence two Killing spinor, including a new class admitting only exceptional Killing tensors. A connection is established with the classification of locally rotati
Externí odkaz:
http://arxiv.org/abs/1408.4258
Autor:
Bergh, Norbert Van den
The 1+3 covariant equations, embedded in an extended tetrad formalism and describing a space-time with an arbitrary energy-momentum distribution, are reconsidered. It is shown that, provided the 1+3 splitting is performed with respect to a generic ti
Externí odkaz:
http://arxiv.org/abs/1302.6448
We prove that the vorticity or the expansion vanishes for any shear-free perfect fluid solution of the Einstein field equations where the pressure satisfies a barotropic equation of state and the spatial divergence of the electric part of the Weyl te
Externí odkaz:
http://arxiv.org/abs/1201.4241