Charged black holes in generalized dilaton-axion gravity (original) (raw)

On the Energy of Charged Black Holes in Generalized Dilaton-Axion Gravity

International Journal of Theoretical Physics, 2010

In this paper we calculate the energy distribution of some charged black holes in generalized dilaton-axion gravity. The solutions correspond to charged black holes arising in a Kalb-Ramond-dilaton background and some existing non-rotating black hole solutions are recovered in special cases. We focus our study to asymptotically flat and asymptotically non-flat types of solutions and resort for this purpose to the Møller prescription. Various aspects of energy are also analyzed.

Exact asymptotically flat charged hairy black holes with a dilaton potential

Journal of High Energy Physics, 2013

We find broad classes of exact 4-dimensional asymptotically flat black hole solutions in Einstein-Maxwell theories with a non-minimally coupled dilaton and its non-trivial potential. We consider a few interesting limits, in particular, a regular generalization of the dilatonic Reissner-Nordström solution and, also, smooth deformations of supersymmetric black holes. Further examples are provided for more general dilaton potentials. We discuss the thermodynamical properties and show that the first law is satisfied. In the non-extremal case the entropy depends, as expected, on the asymptotic value of the dilaton. In the extremal limit, the entropy is determined purely in terms of charges and is independent of the asymptotic value of the dilaton. The attractor mechanism can be used as a criterion for the existence of the regular solutions. Since there is a 'competition' between the effective potential and dilaton potential, we also obtain regular extremal black hole solutions with just one U(1) gauge field turned on.

Dilaton gravity, (quasi-) black holes, and scalar charge

General Relativity and Gravitation

Electrically charged dust is considered in the framework of Einstein-Maxwelldilaton gravity with a Lagrangian containing the interaction term P (χ)F µν F µν , where P (χ) is an arbitrary function of the dilaton scalar field χ , which can be normal or phantom. Without assumption of spatial symmetry, we show that static configurations exist for arbitrary functions g 00 = exp(2γ(x i)) (i = 1, 2, 3) and χ = χ(γ). If χ = const , the classical Majumdar-Papapetrou (MP) system is restored. We discuss solutions that represent black holes (BHs) and quasi-black holes (QBHs), deduce some general results and confirm them by examples. In particular, we analyze configurations with spherical and cylindrical symmetries. It turns out that cylindrical BHs and QBHs cannot exist without negative energy density somewhere in space. However, in general, BHs and QBHs can be phantom-free, that is, can exist with everywhere nonnegative energy densities of matter, scalar and electromagnetic fields.

Charged dilaton black holes with unusual asymptotics

Nuclear Physics B, 1995

We present a new class of black hole solutions in Einstein-Maxwell-dilaton gravity in n ≥ 4 dimensions. These solutions have regular horizons and a singularity only at the origin. Their asymptotic behavior is neither asymptotically flat nor (anti-) de Sitter. Similar solutions exist for certain Liouville-type potentials for the dilaton.

Charged rotating dilaton black holes with Kaluza-Klein asymptotics

Physical Review D, 2016

We construct a class of stationary and axisymmetric solutions to the 5D Einstein-Maxwell-dilaton gravity, which describe configurations of charged rotating black objects with Kaluza-Klein asymptotics. The solutions are constructed by uplifting a vacuum seed solution to six dimensions, performing a boost, and a subsequent circle reduction. We investigate the physical properties of the charged solutions, and obtain their general relations to the properties of the vacuum seed. We also derive the gyromagnetic ratio and the Smarr-like relations. As particular cases we study three solutions, which describe a charged rotating black string, a charged rotating black ring on Kaluza-Klein bubbles, and a superposition of two black holes and a Kaluza-Klein bubble.

Electrically Charged Einstein-Born-Infeld Black Holes with Massive Dilaton

2001

We numerically construct static and spherically symmetric electrically charged black hole solutions in Einstein-Born-Infeld gravity with massive dilaton. The numerical solutions show that the dilaton potential allows many more black hole causal structures than the massless dilaton. We find that depending on the black hole mass and charge and the dilaton mass the black holes can have either one, two, or three horizons. The extremal solutions are also found out. As an interesting peculiarity we note that there are extremal black holes with an inner horizon and with triply degenerated horizon.

Particle Motion around Charged Black Holes in Generalized Dilaton-Axion Gravity

Advances in High Energy Physics

The behaviour of massive and massless test particles around asymptotically flat and spherically symmetric, charged black holes in the context of generalized dilaton-axion gravity in four dimensions is studied. All the possible motions are investigated by calculating and plotting the corresponding effective potential for the massless and massive particles as well. Further, the motion of massive (charged or uncharged) test particles in the gravitational field of charged black holes in generalized dilaton-axion gravity for the cases of static and nonstatic equilibrium is investigated by applying the Hamilton-Jacobi approach.

On uniqueness of static Einstein-Maxwell-dilaton black holes

2001

We prove uniqueness of static, asymptotically flat spacetimes with non-degenerate black holes for three special cases of Einstein-Maxwell-dilaton theory: For the coupling ``$\alpha = 1$'' (which is the low energy limit of string theory) on the one hand, and for vanishing magnetic or vanishing electric field (but arbitrary coupling) on the other hand. Our work generalizes in a natural, but non-trivial way the uniqueness result obtained by Masood-ul-Alam who requires both alpha=1\alpha = 1alpha=1 and absence of magnetic fields, as well as relations between the mass and the charges. Moreover, we simplify Masood-ul-Alam's proof as we do not require any non-trivial extensions of Witten's positive mass theorem. We also obtain partial results on the uniqueness problem for general harmonic maps.

A local characterization for static charged black holes

Classical and Quantum Gravity, 2010

We obtain a purely local characterisation that singles out the Majumdar-Papapetrou class, the near-horizon Bertotti-Robinson geometry and the Reissner-Nordström exterior solution, together with its plane and hyperbolic counterparts, among the static electrovacuum spacetimes. These five classes are found to form the whole set of static Einstein-Maxwell fields without sources and conformally flat space of orbits, this is, the conformastat electrovacuum spacetimes. The main part of the proof consists in showing that a functional relationship between the gravitational and electromagnetic potentials must always exist. The classification procedure provides also an improved characterisation of Majumdar-Papapetrou, by only requiring a conformally flat space of orbits with a vanishing Ricci scalar of the usual conveniently rescaled 3-metric. A simple global consideration allows us to state that the asymptotically flat subset of the Majumdar-Papapetrou class and the Reissner-Nordström exterior solution are the only asymptotically flat conformastat electrovacuum spacetimes.

Non-asymptotically flat, non-dS/AdS dyonic black holes in dilaton gravity

Classical and Quantum Gravity, 2005

We present exact spherically symmetric dyonic black hole solutions in four-dimensional and higher dimensional Einstein Maxwell-dilaton gravity with Liouville-type potentials for the dilaton field. These solutions have unusual asymptotics---they are neither asymptotically flat nor asymptotically (anti-)de Sitter. The solutions have one or two horizons hiding a curvature singularity at the origin. A class of topological dyonic black holes with topology