The presence and evolution of apparent horizons in a two-parameter family of spherically symmetric, time-dependent solutions of Brans-Dicke gravity are analyzed. These solutions were introduced to model space- and time-varying gravitational couplings and are supposed to represent central objects embedded in a spatially flat universe.We find that the solutions possess multiple evolving apparent horizons, both black hole horizons covering a central singularity and cosmological ones. It is not uncommon for two of these horizons to merge, leaving behind a naked singularity covered only by a cosmological horizon. Two characteristic limits are also explicitly worked out: the limit where the theory reduces to general relativity and the limit where the solutions become static. The physical relevance of this family of solutions is discussed.
|Titolo:||Dynamical apparent horizons in inhomogeneous Brans-Dicke universes|
|Autori:||Faraoni V; Vitagliano V; Sotiriou T P; Liberati S|
|Rivista:||PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY|
|Data di pubblicazione:||2012|
|Digital Object Identifier (DOI):||10.1103/PhysRevD.86.064040|
|Appare nelle tipologie:||1.1 Journal article|