200 citations · 2k across the 79 of their papers we have counts for
82 papers
Partial geometrization of dark matter in metric gravity: Exact reconstruction and growth constraints
Davide Campanella Galanti, Oliver F. Piattella
We ask what fraction of dark matter can be accounted for by the geometry of a stable metric theory, requiring the expansion history to be exactly equal to that of the CDM…
Geodesics in Black-Hole Spacetimes: A Qualitative Classification Using Vieta's Formulae
Oliver F. Piattella
This monograph classifies the geodesics of the Schwarzschild, Kerr and Schwarzschild-de Sitter black holes without solving for their turning points. In all three spacetimes, the ra…
A nonlinear Newtonian approximation to General Relativity
Oliver F. Piattella
We investigate a nonrelativistic approximation to general relativity that does not require the metric coefficients to be weak perturbations of the Minkowski metric. Instead, we ass…
More on the relativistic images produced in gravitational lensing
Angelika Ghazale, Oliver F. Piattella
We investigate the gravitational lensing properties and the formation of relativistic images associated with black holes modeled by the Reissner-Nordström and Kerr space-time geome…
Dark Coriolis Fields
Gabriele Bianchi, Federico Re, Oliver Fabio Piattella
We argue that the standard post-Newtonian expansion scheme used in General Relativity leaves room for time-space components of the metric to be of the same order of the us…
The matter with(in) CPL
Leonardo Giani, Rodrigo Von Marttens, Oliver Fabio Piattella
We introduce a two-parameter phenomenological extension of the CDM model in which the equation of state parameter of the ``dust'' fluid becomes different from zero for redshifts…
Non zero Coriolis field in Ehlers' Frame Theory
Federico Re, Oliver F. Piattella
Ehlers' Frame Theory is a class of geometric theories parameterized by and identical to the General Theory of Relativity for . The limit does not reco…
Tilt in quadratic gravity II
Waleska P. F. de Medeiros, Daniel Müller, Oliver F. Piattella +2
We investigate a tilted fluid component on a Bianchi V geometry in the theories of General Relativity (GR) and Quadratic Gravity (QG). The main objective of this work is the study…
Asymptotically Schwarzschild solutions in extension of general relativity
Federico Scali, Oliver Fabio Piattella
We address the question of how to build a class of extensions of General Relativity which are compatible with solar system experiments, without making any preliminary assump…
Bayesian analysis of a Unified Dark Matter model with transition: can it alleviate the tension?
Emmanuel Frion, David Camarena, Leonardo Giani +4
We consider cosmological models in which Dark Matter (DM) and Dark Energy (DE) are described by a single component, dubbed Unified Dark Matter (UDM) models, in which the DE-like pa…
Induced non-local cosmology
Leonardo Giani, Oliver Fabio Piattella
We investigate the cosmological implications of an effective gravitational action, inspired by Sakharov's idea of induced gravity, containing non-local contributions from the opera…
Gravitational lensing in a universe with matter and a cosmological constant
Pedro Bessa, Oliver F. Piattella
We extend the results obtained in \cite{Piattella_2016, mcvittie_2015} and \cite{Park_2008} for gravitational lensing in the McVittie metric by including the effect of the transiti…
Bianchi IX gravitational collapse of matter inhomogeneities
Leonardo Giani, Oliver F. Piattella, Alexander Yu. Kamenshchik
We investigate a model of gravitational collapse of matter inhomogeneities where the latter are modelled as Bianchi type IX (BIX) spacetimes. We found that this model contains, as…
Impact of inhomogeneities on slowly rolling Quintessence: implications for the local variations of the fine-structure constant
Leonardo Giani, Emmanuel Frion, Oliver Fabio Piattella
We study how the evolution of a Dark Energy Quintessence fluid is modified by the presence of a matter inhomogeneity. To do so, we study linear perturbations of a flat FLRW backgro…
On Rastall gravity formulation as a and a theory
Júlio C. Fabris, Oliver F. Piattella, Davi C. Rodrigues
Rastall introduced a stress-energy tensor whose divergence is proportional to the gradient of the Ricci scalar. This proposal leads to a change in the form of the field equations o…
Inflation with sterile scalar coupled to massive fermions and to gravity
Jessica S. Martins, Oliver F. Piattella, Ilya L. Shapiro +1
In the recent paper [3] it was shown that the consistency of the quantum theory of a sterile scalar coupled to massive fermions requires the inclusion of odd-power terms in the pot…
Rastall's theory of gravity: Spherically symmetric solutions and the stability problem
K. A. Bronnikov, Júlio C. Fabris, Oliver F. Piattella +2
We study the stability of static, spherically symmetric solutions of Rastall's theory in the presence of a scalar field with respect to spherically symmetric perturbations. It is s…
Does the cosmological constant stay hidden?
Oliver F. Piattella
We elaborate on the proposal of [Phys. Rev. Lett. 123 (2019) 13, 131302], about the possibility of hiding the cosmological constant in the complicated topology that one expects to…
Transient weak gravity in scalar-tensor theories
Manuel Wittner, Giorgio Laverda, Oliver F. Piattella +1
Sub-horizon perturbations in scalar-tensor theories have been shown to grow generically faster than in uncoupled models due to a positive, additive Yukawa force. In such cases, the…
Quantum Cosmology of Fab Four John Theory with Conformable Fractional Derivative
Isaac Torres, Júlio César Fabris, Oliver Fabio Piattella +1
We study a quantization via fractional derivative of a nonminimal derivative coupling cosmological theory, namely, the Fab Four John theory. Its Hamiltonian version presents the is…
Bouncing and Cyclic Quantum Primordial Universes and the Ordering Problem
Isaac Torres, Júlio César Fabris, Oliver Fabio Piattella
In a Bohmian quantum cosmology scenario, we investigate some quantum effects on the evolution of the primordial universe arising from the adoption of an alternative non-trivial ord…
An Introduction to Particle Dark Matter
Stefano Profumo, Leonardo Giani, Oliver F. Piattella
We review the features of Dark Matter as a particle, presenting some old and new instructive models, and looking for their physical implications in the early universe and in the pr…
Neutron star masses in -gravity
Fulvio Sbisà, Pedro O. Baqui, Tays Miranda +2
We address the issue of the existence of inequivalent definitions of gravitational mass in -gravity. We present several definitions of gravitational mass, and discuss the fo…
Late-times asymptotic equation of state for a class of nonlocal theories of gravity
Leonardo Giani, Oliver Fabio Piattella
We investigate the behavior of the asymptotic late-times effective equation of state for a class of nonlocal theories of gravity. These theories modify the Einstein-Hilbert Lagrang…