7 papers
Ultracompact Anisotropic Stars and Gravastars in General Relativity
Prajwal Hassan Puttasiddappa, Nora Bretón, Santiago Esteban Perez Bergliaffa
We study static, spherically symmetric ultracompact objects in General Relativity with anisotropic stress. Using the covariant anisotropic equation of state and assuming homogeneou…
Another Look at the Weak-Field Limit of Generalized Hybrid Metric-Palatini Gravity
Gustavo Melgarejo, Santiago Esteban Perez Bergliaffa
We investigate the weak-field regime of generalized hybrid metric-Palatini theories, described by a generic function \(f(R,\mathcal{R})\), where \(R\) is the metric Ricci scalar an…
Light Deflection due to Spinoptic Effects in Parametrized and Spherically Symmetric Hairy Black Holes
Kelvin S. Alves, Rogerio T. Cavalcanti, Santiago E. Perez Bergliaffa
In the standard geometric optics approximation, null rays propagating in a spherically symmetric black hole background follow planar geodesics. This picture changes, however, when…
Does a wormhole survive a cosmological bounce?
Daniela Pérez, Gustavo E. Romero, Santiago E. Perez Bergliaffa
We investigate whether a dynamical wormhole could survive in a universe that undergoes a cosmological bounce. First, the conditions under which a wormhole could persist from a cont…
A connection between Gravitational Scalar-Tensor theories and Generalized Hybrid theories
Jonathan RamÃrez, Santiago Esteban Perez Bergliaffa
We establish a correspondence between higher-derivative gravitational scalar-tensor theories of the form and generalized hybrid metric-Palatini models $…
Scalar-tensor theories in the Lyra geometry: Invariance under local transformations of length units and the Jordan-Einstein frame conundrum
E. C. Valadão, Felipe Sobrero, Santiago Esteban Perez Bergliaffa
The Lyra geometry provides an interesting approach to develop purely geometrical scalar-tensor theories. Here we present a theory on Lyra manifolds which contains generalizations o…