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Eloy Ayón-Beato

Publications and source records attributed to Eloy Ayón-Beato.

48 records · Page 3Linked to original sources
arXiv2001

Inflationary scenarios with scale-invariant spectral tensorial index

Next-to-leading order expressions related to Stewart-Lyth inverse problem are used to determine the inflationary models with a tensorial power spectrum described by a scale-invariant spectral index. Beyond power-law inflation, solutions are characterized by scale dependent scalar indices. These models can be used as assumption on the generation of primordial perturbations to test for scale dependence of the scalar index at large angular scales. If such a dependence is detected, a nonzero contribution of gravitational waves to the CMB spectrum must be expected.

astro-ph↗
arXiv2001

Static Black Holes of Metric-Affine Gravity in the Presence of Matter

We investigate spherically symmetric and static gravitational fields representing black hole configurations in the framework of metric-affine gauge theories of gravity (MAG) in the presence of different matter fields. It is shown that in the triplet ansatz sector of MAG, black hole configurations in the presence of non-Abelian matter fields allow the existence of black hole hair. We analyze several cases of matter fields characterized by the presence of hair and for all of them we show the validity of the no short hair conjecture.

gr-qc↗
arXiv2001

Note on Scalar Fields Non-Minimally Coupled to (2+1)-Gravity

Scalar fields non--minimally coupled to (2+1)-gravity, in the presence of cosmological constant term, are considered. Non-minimal couplings are described by the term $ζR Ψ^2$ in the Lagrangian. Within a class of static circularly symmetric space-times, it is shown that the only existing physically relevant solutions are the anti-de Sitter space-time for $ζ=0$, and the Martinez-Zanelli black hole for $ζ=1/8$. We obtain also two new solutions with non-trivial scalar field, for $ζ=1/6$ and $ζ=1/8$ respectively, nevertheless, the corresponding space-times can be reduced, via coordinate transformations, to the standard anti-de Sitter space.

gr-qc↗
arXiv2000

Stewart-Lyth Inverse Problem

In this paper the Stewart-Lyth inverse problem is introduced. It consists of solving two non-linear differential equations for the first slow-roll parameter and finding the inflaton potential. The equations are derived from the Stewart--Lyth equations for the scalar and tensorial perturbations produced during the inflationary period. The geometry of the phase planes transverse to the trajectories is analyzed, and conclusions about the possible behaviour for general solutions are drawn.

astro-ph↗
arXiv2000

No-Hair Theorem for Spontaneously Broken Abelian Models in Static Black Holes

The vanishing of the electromagnetic field, for purely electric configurations of spontaneously broken Abelian models, is established in the domain of outer communications of a static asymptotically flat black hole. The proof is gauge invariant, and is accomplished without any dependence on the model. In the particular case of the Abelian Higgs model, it is shown that the only solutions admitted for the scalar field become the vacuum expectation values of the self-interaction.

gr-qc↗
arXiv2000

The Bardeen Model as a Nonlinear Magnetic Monopole

The Bardeen model -- the first regular black hole model in General Relativity -- is reinterpreted as the gravitational field of a nonlinear magnetic monopole, i.e., as a magnetic solution to Einstein equations coupled to a nonlinear electrodynamics.

gr-qc↗
arXiv2000

On the Stewart-Lyth Inverse Problem

In this paper the Stewart-Lyth inverse problem is rewritten using the comoving scales as the basic parameter. It is shown that some information on the inflaton potential can be obtained from observations taking into account only the scalar power spectrum.

astro-ph↗
arXiv1999

New Regular Black Hole Solution from Nonlinear Electrodynamics

Using a nonlinear electrodynamics coupled to General Relativity a new regular exact black hole solution is found. The nonlinear theory reduces to the Maxwell one in the weak limit, and the solution corresponds to a charged black hole for |q| \leq 2s_c m \approx 1.05 m, with metric, curvature invariants, and electric field regular everywhere.

hep-th↗
arXiv1999

Non-Singular Charged Black Hole Solution for Non-Linear Source

A non-singular exact black hole solution in General Relativity is presented. The source is a non-linear electromagnetic field, which reduces to the Maxwell theory for weak field. The solution corresponds to a charged black hole with |q| \leq 2s_c m \approx 0.6 m, having metric, curvature invariants, and electric field bounded everywhere.

gr-qc↗
arXiv1999

Uniqueness theorems for static black holes in metric-affine gravity

Using the equivalence theorem for the triplet ansatz sector of metric-affine gravity (MAG) theories and the Einstein-Proca system, it is shown that the only static black hole of the triplet sector of MAG is the Schwarzschild solution, under the constraint (-4β_4 + k_1β_5/2k_0 + k_2γ_4/k_0)/κz_4 \neq 0 on the coupling constants. For the special case (-4β_4 + k_1β_5/2k_0 + k_2γ_4/k_0)/κz_4 = 0, it follows that the only static non-extremal black hole is the Reissner-Nordström one. The results can be extended to exclude also the existence of soliton solutions of the triplet sector of MAG.

gr-qc↗
arXiv1999

Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

The first regular exact black hole solution in General Relativity is presented. The source is a nonlinear electrodynamic field satisfying the weak energy condition, which in the limit of weak field becomes the Maxwell field. The solution corresponds to a charged black hole with |q| \leq 2 s_c m \approx 0.6 m, having the metric, the curvature invariants, and the electric field regular everywhere.

gr-qc↗