Charged Dilaton Black Holes Research Articles

Hawking radiation of linear dilaton black holes

We compute exactly the semi-classical radiation spectrum for a class of non-asymptotically flat charged dilaton black holes, the so-called linear dilaton black holes. In the high frequency regime, the temperature for these black holes generically agrees with the surface gravity result. In the special case where the black hole is massless, we show that, although the surface gravity remains finite, there is no radiation, in agreement with the fact that massless objects cannot radiate.

Particle motion and gravitational lensing in the metric of a dilaton black hole in a de Sitter universe

We consider the metric exterior to a charged dilaton black hole in a de Sitter universe. We study the motion of a test particle in this metric. Conserved quantities are identified and the Hamilton-Jacobi method is employed for the solutions of the equations of motion. At large distances from the black hole the Hubble expansion of the universe modifies the effective potential such that bound orbits could exist up to an upper limit of the angular momentum per mass for the orbiting test particle. We then study the phenomenon of strong field gravitational lensing by these black holes by extending the standard formalism of strong lensing to the non-asymptotically flat dilaton-de Sitter metric. Expressions for the various lensing quantities are obtained in terms of the metric coefficients.

Global properties of charged dilatonic Gauss-Bonnet black holes

We study the phase space of the spherically symmetric solutions of Einstein-Maxwell-Gauss-Bonnet system nonminimally coupled to a scalar field and prove the existence of solutions with unusual asymptotics in addition to asymptotically flat ones. We also find new dyonic solutions of dilatonic Einstein-Maxwell theory.

Thermodynamics of [formula omitted] dilatonic black holes in global flat embedding scheme

We study thermodynamics of (1+1)-dimensional dilatonic black holes in global embedding Minkowski space scheme. Exploiting geometrical entropy correction we construct consistent entropy for the charged dilatonic black hole. Moreover, (1+1) dilatonic black holes with higher order terms are shown to possess (3+2) global flat embedding structures regardless of the details of the lapse function, and to yield a generic entropy.

Topological black holes in dilaton gravity theory

The static solutions of electrically and magnetically charged dilaton black holes with the topology of R2⊗Sn−2, R2⊗S1⊗Sn−3 and R2⊗R1⊗Sn−3 are constructed from the dilaton gravity theory with a cosmological constant. The spacetime structure of the resulted solutions is studied.

Greybody factors of charged dilaton black holes in 2 + 1 dimensions

We have studied scalar perturbations of charged dilaton black holes in 2+1 dimensions. The black hole considered here is a solution to the low-energy string theory in 2+1 dimensions. The exact decay rates and the grey body factors for the massless minimally coupled scalar is computed for both the charged and the uncharged dilaton black holes. The charged and the uncharged black hole show similar behavior for grey body factors, reflection coefficients and decay rates.

Asymptotic states in two black hole moduli space

We discuss the quantum states in the moduli space, which constructed with maximally charged dilaton black holes. Considering the quantum mechanics in the moduli space, we obtain the asymptotic states for the near-coincident black holes and the widely separated black holes. We study the scattering process of the dilaton black holes with the asymptotic states. In the scattering process, the quantum effects in the black hole moduli space are investigated.

Scalar Perturbations of Charged Dilaton Black Holes

We have studied the scalar perturbation of static charged dilaton black holes in 3+1 dimensions. The black hole considered here is a solution to the low-energy string theory in 3+1 dimensions. The quasinormal modes for the scalar perturbations are calculated using the third order WKB method. The dilaton coupling constant has a considerable effect on the values of quasi normal modes. It is also observed that there is a linear relation between the quasi normal modes and the temperature for large black holes.

Quasinormal Modes of Charged Dilaton Black Holes in 2 + 1 Dimensions

We have studied the scalar perturbation of static charged dilaton black holes in 2 + 1 dimensions. The black hole considered here is a solution to the low-energy string theory in 2 + 1 dimensions. It is asymptotic to the anti-de Sitter space. The exact values of quasinormal modes for the scalar perturbations are calculated. For both the charged and uncharged cases, the quasinormal frequencies are pure-imaginary leading to purely damped modes for the perturbations.

Quantum scattering in two black hole moduli space

We discuss the quantum scattering process in the moduli space consisting of two maximally charged dilaton black holes. The black hole moduli space geometry has different structures for arbitrary dimensions and various values of dilaton coupling. We study the quantum effects of the different moduli space geometries with scattering process. Then, it is found that there is a resonance state on certain moduli spaces.

Varying α and black hole entropy

Recently it has been suggested that an increase in the fine structure constant alpha with time would decrease the entropy of a Reissner-Nordstrom black hole, thereby violating the second law of thermodynamics. In this note we point out that, at least for a certain class of charged dilaton black holes related to string theory, the entropy does not change under adiabatic variations of alpha and one might expect it to increase for non-adiabatic changes.

Thick domain walls and charged dilaton black holes

We study a black hole domain wall system in dilaton gravity which is the low-energy limit of the superstring theory. We solve numerically equations of motion for real self-interacting scalar field and justify the existence of static axisymmetric field configuration representing the thick domain wall in the background of a charged dilaton black hole. It was also confirmed that the extreme dilaton black hole always expelled the domain wall.

Conformal quantum mechanics in two-black-hole moduli space

We discuss quantum mechanics in the moduli space consisting of two maximally charged dilaton black holes. The quantum mechanics of the two black hole system is similar to the one of DFF model, and this system has the $SL(2,R)$ conformal symmetry. Also, we discuss the bound states in this system.

Letter: Quasinormal Modes of the Electrically Charged Dilaton Black Hole

We sketch the results of calculations of the quasinormal frequencies of the electrically charged dilaton black hole. At the earlier phase of evaporation (Q is less than 0.7–0.8M), the dilaton black hole “rings” with the complex frequencies which differ negligibly from those of the Reissner-Nordström black hole. The spectrum of the frequencies weakly depends upon the dilaton coupling.

Quasilocal Energy for Static Charged Black Holes in String Theory

The Brown–York quasilocal energies of some static charged dilaton black holes are calculated, and then the validity of Martinez's conjecture is explored in string theory. It is shown that the energy is positive and monotonically decreases to the ADM mass at spatial infinity, and the conjecture that the Brown–York quasilocal energy at the outer horizon of black hole reduces to twice of its irreducible mass is still applicable for the static charged black holes in string theory. The result is different from Bose–Naing's one.

Distorted charged dilaton black holes

We construct exact static, axisymmetric solutions ofEinstein-Maxwell-dilaton gravity presenting distorted charged dilatonblack holes. The thermodynamics of such distorted blackholes is also discussed.

Bogoliubov coefficients of 2D charged black holes

We exactly calculate the thermal distribution and temperature of Hawking radiation for a two-dimensional charged dilatonic black hole after it has settled down to an “equilibrium” state. The calculation is carried out using the Bogoliubov coefficients. The background of the process is furnished by a preexisting black hole and not by collapsing matter as considered by Giddings and Nelson for the case of a Schwarzschild black hole. Furthermore, the vanishing of the temperature and/or the Hawking radiation in the extremal case is obtained as a regular limit of the general case.

CHARGED DILATONIC BLACK HOLE AND TEST PARTICLES

We present a detailed analysis of the motion of test particles around a charged dilatonic black hole, using the Hamilton–Jacobi (HJ) formalism. We have considered test particles with various masses, electric charges and dilatonic charges and examine its behavior both in static and nonstatic cases.

EXACT STATIC SOLUTIONS IN FOUR-DIMENSIONAL EINSTEIN–MAXWELL-DILATON GRAVITY

Classes of exact static solutions in four-dimensional Einstein–Maxwell-dilaton gravity are found. Besides the well-known solutions previously found in the literature, new solutions are presented. It is shown that spherically symmetric solutions, except for the case of a charged dilaton black hole, represent globally naked strong curvature singularities.

LETTER: Newman–Janis Method and Rotating Dilaton-Axion Black Hole

It is shown that the dilaton-axion rotating black hole solution can be obtained from GGHS static charged dilaton black hole solution via the Newman–Janis method.