2k citations · 12k across the 281 of their papers we have counts for
13 papers · 1 filter
Noncommutative Quantum Cosmology
C. Bastos, O. Bertolami, N. Dias +1
One presents a phase-space noncommutative extension of Quantum Cosmology in the context of a Kantowski-Sachs (KS) minisuperspace model. We obtain the Wheeler-DeWitt (WDW) equation…
Stability Conditions For a Noncommutative Scalar Field Coupled to Gravity
Orfeu Bertolami, Carlos A. D. Zarro
We consider a noncommutative scalar field with a covariantly constant noncommutative parameter in a curved space-time background. For a potential as a noncommutative polynomial it…
Some new reflections on Mr. Palomar
Orfeu Bertolami
The character Mr. Palomar, the alter-ego of the Italian author Italo Calvino, appeared for the first time in 1975 on the pages of the "Il Corriere della Sera", and then more or les…
Non-minimal curvature-matter couplings in modified gravity
Orfeu Bertolami, Tiberiu Harko, Francisco S. N. Lobo +1
Recently, in the context of f(R) modified theories of gravity, it was shown that a curvature-matter coupling induces a non-vanishing covariant derivative of the energy-momentum, im…
Estimating radiative momentum transfer through a thermal analysis of the Pioneer Anomaly
O. Bertolami, F. Francisco, P. J. S. Gil +1
A methodology based on point-like sources is discussed, enabling a reliable estimate of the acceleration of the Pioneer 10 and 11 probes caused by thermal effects. A sensitivity an…
Thermal Analysis of the Pioneer Anomaly: A method to estimate radiative momentum transfer
Orfeu Bertolami, Frederico Francisco, Paulo J. S. Gil +1
We present a methodology based on point-like Lambertian sources that enables one to perform a reliable and comprehensive estimate of the overall thermally induced acceleration of t…
Nonminimal coupling of perfect fluids to curvature
Orfeu Bertolami, Francisco S. N. Lobo, Jorge Páramos
In this work, we consider different forms of relativistic perfect fluid Lagrangian densities, that yield the same gravitational field equations in General Relativity. A particularl…
A new source for a braneworld cosmological constant from a modified gravity model in the bulk
Orfeu Bertolami, Carla Carvalho, Joao Laia
We show that a four-dimensional equation of state for a cosmological constant term arises from a perfect fluid in the bulk in the context of a gravity model where the scalar curvat…
WMAP5 constraints on the unified model of dark energy and dark matter
T. Barreiro, O. Bertolami, P. Torres
We derive constraints on the parameter space of the unified model of dark energy and dark matter, the Generalized Chaplygin Gas (GCG), from the amplitudes and positions of the firs…
On the non-minimal gravitational coupling to matter
O. Bertolami, J. Páramos
The connection between theories of gravity and scalar-tensor models with a "physical" metric coupled to the scalar field is well known. In this work, we pursue the equivalen…
Stationary condition in a perturbative approach for mass varying neutrinos
Alex E. Bernardini, O. Bertolami
A perturbative approach for arbitrary choices of the equation of state of the universe is introduced in order to treat scenarios for mass varying neutrinos (MaVaN's) coupled to the…
Lorentz violating extension of the Standard Model and the Beta-decay end-point
Alex E. Bernardini, O. Bertolami
The Standard Model extension with additional Lorentz violating terms allows for redefining the equation of motion of a propagating left-handed fermionic particle. The obtained Dira…
The mystical formula and the mystery of Khronos
Orfeu Bertolami
In 1908, Minkowski put forward the idea that invariance under what we call today the Lorentz group, , would be more meaningful in a four-dimensional space-time co…