arXiv subjects

M. Campos

Publications and source records attributed to M. Campos.

4 recordsLinked to original sources

arXiv2019

Final fate of Kantowski-Sachs gravitational collapse

Although it is not a fundamental question, to determine exact and general solutions for a given theory has advantages over a numerical integration in many specific cases. Of course, respecting the peculiarities of the problem. Revisiting the integration of the General Relativity Theory field equations for the Kantowski-Sachs spacetime, that describes a homogeneous but anisotropic universe whose spatial section has the topology of $R \times S^2$, we integrate the equations for arbitrary curvature parameter, and writing the solutions considering the process of gravitational collapse. We took the opportunity and made some comments involving some features of the model such as: energy density, shear, viscosity, and the production of gravitational waves via Petrov classification.

gr-qc↗

arXiv2015

The cosmic censorship conjecture in a higher dimensional spacetime with an interacting vacuum energy

Presently, the inclusion of the vacuum energy in the energy momentum tensor, and the inclusion of the extra dimensions in the spacetime, can not be rule out of the research in gravitation. In this work we study the influence of the vacuum energy in the collapse process of a stellar fluid, and consequently for the cosmic censorship conjecture, considering a homogeneous and isotropic spacetime with arbitrary number of dimensions. We discuss the active gravitational mass of the black hole formed, where the vacuum energy and the number of dimensions has a crucial role in the process.

gr-qc↗

arXiv2013

Black Hole Formation with an Interacting Vacuum Energy Density: Curvature Effects

The gravitational collapse of a spherically symmetric massive core of a star in which the fluid component is interacting with a growing vacuum energy density filling a FLRW type geometry with an arbitrary curvature parameter is investigated. The complete set of exact solutions for all values of the free parameters are obtained and the influence of the curvature term on the collapsing time, black hole mass and other physical quantities are also discussed in detail. We show that for the same initial conditions the total black hole mass depends only on the effective matter density parameter (including the vacuum component). It is also shown that the analytical condition to form a black hole i.e. the apparent horizon is not altered by the contribution of the curvature terms, however, the remaining physical quantities are quantitatively modified.

gr-qc↗

arXiv2012

Black Hole Formation with an Interacting Vacuum Energy Density

We discuss the gravitational collapse of a spherically symmetric massive core of a star in which the fluid component is interacting with a growing vacuum energy density. The influence of the variable vacuum in the collapsing core is quantified by a phenomenological β-parameter as predicted by dimensional arguments and the renormalization group approach. For all reasonable values of this free parameter, we find that the vacuum energy density increases the collapsing time but it cannot prevent the formation of a singular point. However, the nature of the singularity depends on the values of β. In the radiation case, a trapped surface is formed for β<1/2 whereas for β>1/2, a naked singularity is developed. In general, the critical value is β=1-2/3(1+ω), where the ω-parameter describes the equation of state of the fluid component.

gr-qc↗