Imperfect fluid description of modified gravities
Abstract
The Brans-Dicke-like field of scalar-tensor gravity can be described as an imperfect fluid in an approach in which the field equations are regarded as effective Einstein equations. After completing this approach, we recover, as a special case, the known effective fluid for a scalar coupled nonminimally to the Ricci curvature, and we describe the imperfect fluid equivalent of f (R ) gravity. A symmetry of electrovacuum Brans-Dicke gravity is translated into a symmetry of the corresponding effective fluid. The discussion is valid for any spacetime geometry.
- Publication:
-
Physical Review D
- Pub Date:
- October 2018
- DOI:
- 10.1103/PhysRevD.98.084019
- arXiv:
- arXiv:1808.02427
- Bibcode:
- 2018PhRvD..98h4019F
- Keywords:
-
- General Relativity and Quantum Cosmology
- E-Print:
- Added some explanation in the text, typographical errors corrected. Matches version to appear in Phys. Rev. D