72 citations · 284 across the 14 of their papers we have counts for
11 papers · 1 filter
Neutron stars in gravity with conserved energy-momentum tensor: Hydrostatic equilibrium and asteroseismology
Juan M. Z. Pretel, Sergio E. Jorás, Ribamar R. R. Reis +1
We investigate the equilibrium and radial stability of spherically symmetric relativistic stars, considering a polytropic equation of state (EoS), within the framework of …
Strongest constraint in gravity: stellar stability
Juan M. Z. Pretel, Sergio E. Jorás, Ribamar R. R. Reis
In the metric approach of theories of gravity, the fourth-order field equations are often recast as effective Einstein equations in the presence of standard matter and a cur…
Massive scalar wave packet emission by a charged Black Hole and Cosmic Censorship Conjecture violation
Rodrigo L. Fernandez, Ribamar R. R. Reis, Sergio E. Jorás
We study the tunneling probability of a massive () uncharged scalar packet out from a near-extremal, static charged black hole (with mass and charge ). We sho…
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…
Pressure effects in the weak-field limit of f(R) = R + alpha R^2 gravity
Fulvio Sbisà, Oliver F. Piattella, Sergio E. Jorás
We investigate the linear regime of f(R) = R + alpha R^2 gravity for static, spherically symmetric and asymptotically flat configurations of matter. We show that, in vacuum and dee…
Hadamard state in Schwarzschild-de Sitter spacetime
Marcos Brum, Sergio E. Jorás
We construct a state in the Schwarzschild-de Sitter spacetime which is invariant under the action of its group of symmetries. Our state is not defined in the whole Kruskal extensio…
Homoclinic Chaos in Axisymmetric Bianchi-IX cosmological models with an "ad hoc" quantum potential
G. C. Corrêa, T. J. Stuchi, S. E. Jorás
In this work we study the dynamics of the axisymmetric Bianchi IX cosmological model with a term of quantum potential added. As it is well known this class of Bianchi IX models are…
Chaos in a closed Friedmann-Robertson-Walker universe: An imaginary approach
S. E. Jorás, T. J. Stuchi
In this work we study the existence of mechanisms of transition to global chaos in a closed Friedmann-Robertson-Walker universe with a massive conformally coupled scalar field. We…
Chaos and Preheating
Sergio E. Jorás, Victor H. Cárdenas
We show evidence for a relationship between chaos and parametric resonance both in a classical system and in the semiclassical process of particle creation. We apply our considerat…
On Perturbations in Warm Inflation
H. P. De Oliveira, S. E. Jorás
Warm inflation is an interesting possibility of describing the early universe, whose basic feature is the absence, at least in principle, of a preheating or reheating phase. Here w…
Minimal Closed Set of Observables in the Theory of Cosmological Perturbations
M. Novello, J. M. Salim, M. C. Motta da Silva +2
The theory of perturbation of Friedman-Robertson-Walker (FRW) cosmology is analysed exclusively in terms of observable quantities. Although this can be a very complete and general…