Destroying a Peldan Electrostatic Solution Black Hole

By throwing a particle with electric charge and angular momentum into the black holes, much evidence shows that the naked singularity of some （3＋1）-dimensional black holes might be seen, which is not allowed in the weak cosmic censorship conjecture. In this study, we consider a （2＋1）-dimensional Peldan black hole and find that it could be destroyed under certain conditions in both extreme and near-extreme cases.

THE SOLUTION OF A CRACK EMANATING FROM AN ARBITRARY HOLE BY BOUNDARY COLLOCATION METHOD

In this paper a group of stress functions has been proposed for the calculation of a crack emanating from a hole with different shape (including circular, elliptical, rectangular, or rhombic hole) by boundary collocation method. The calculation results show that they coincide very well with the existing solutions by other methods for a circular or elliptical hole with a crack in an infinite plate. At the smae time, a series of results for different holes in a finite plate has also been obtained in this paper. The proposed functions and calculation procedure can be used for a plate of a crack emanating from an arbitrary hole.

Gravitational decoupling for hairy black holes in asymptotic AdS spacetimes

In this study,the gravitational decoupling approach via extended geometric deformation is utilized to generate analytical black hole solutions owing to its simplicity and effectiveness.Considering the external fields surrounding Schwarzschild AdS black holes,we derive hairy black hole solutions in asymptotic AdS spacetime,satisfying the strong and dominant energy conditions.Moreover,we find that if the black hole spacetime is a fluid system,the fluid under each of these conditions is anisotropic.

High dimensional AdS-like black hole and phase transition in Einstein-bumblebee gravity

In this study,we obtained an exact high dimensional anti-de Sitter(AdS)black hole solution in Einsteinbumblebee gravity theory.This AdS-like black hole can only exist with a linear functional potential of the bumblebee field.We found that the Smarr formula and the first law of black hole thermodynamics can still be constructed in this Lorentz symmetry breaking black hole spacetime,but the conceptions of the black hole horizon area/entropy and the volume inside the horizon should be renewed due to its anisotropy.We also found that two types of phase transition exist:small-large black hole phase transition and Hawking-Page phase transition,like those of the Schwarzschild AdS black hole.After Lorentz symmetry breaking,the black hole mass at the divergent point of heat capacity becomes small,and the Gibbs free energy of the meta-stable large black hole is also smaller,showing that the large stable black hole can be more easily formed.

Minimizing stress concentrations around an elliptical hole by concentrated forces acting on the uniaxially loaded plate

When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy＇s integral formula. And then, based on the superposition principle, the analyt- ical solutions for stress around an elliptical hole in an infinite plate subjected to a uniform far-field stress and concentrated forces, are obtained. Tangential stress concentration will occur on the hole boundary when only far-field uniform loads are applied. When concen- trated forces are applied in the reversed directions of the uniform loads, tangential stress concentration on the hole boundary can be released significantly. In order to minimize the tangential stress concentration, we need to determine the optimum positions and values of the concentrated forces. Three different optimization methods are applied to achieve this aim. The results show that the tangential stress can be released significantly when the op- timized concentrated forces are applied.

Slowly rotating Einstein-bumblebee black hole solution and its greybody factor in a Lorentz violation model

We obtain an exact slowly rotating Einstein-bumblebee black hole solution by solving the corresponding rr and tθ components of the gravitational field equations for both cases:A)b u=(0,b(r),0,0) and B) bu=(0,b(r),b(θ),0) .Then,we check the other gravitational field equations and the bumblebee field motion equations using this solution.We find that for case A,there indeed exists a slowly rotating black hole solution for an arbitrary LV(Lorentz violation)coupling constant l;however,for case B,this slowly rotating solution exists if and only if coupling constant l is as small as or smaller than angular momentum a.Thus far,no full rotating black hole solution has been published;hence,the Newman-Janis algorithm cannot be used to generate a rotating solution in the Einstein-bumblebee theory.This is similar to the Einstein-aether theory,wherein only some slowly rotating black hole solutions exist.To study the effects of this broken Lorentz symmetry,we consider the black hole greybody factor and find that,for angular index l=0 ,LV constant l decreases the effective potential and enhances the absorption probability,which is similar to the results for the non-minimal derivative coupling theory.