Related papers: The Kerr theorem and multiparticle Kerr-Schild sol…
The model of spinning particle, based on the Kerr-Newman solution with |a}>>m, is discussed. It is shown that the Kerr singular ring can be considered as a string with an orientifold world-sheet. Orientifold adds to the Kerr ring an extra…
We have discovered a new type of scalarized charged black holes in a surprisingly simple system: an Einstein-Maxwell-Klein-Gordon field theory where the three fields couple non-minimally through a Horndeski vector-tensor term. In addition…
Extending the holographic program of [1], we derive f(R) gravity and the Maxwell equations from the holographic principle, using time-like holographic screen. We find that to derive the Einstein equations and f(R) gravity in a natural…
Gravitational and electromagnetic (EM) field of the Dirac electron is described by the Kerr-Newman (KN) solution. We elaborate a regular source of the KN solution which satisfies the requirement of flat space-time inside the source and…
We study particle production aspect in the flat FRW universe in the framework of $f(T)$ gravity. The matter is minimally coupled with the gravity and an exact power-law solution is obtained by solving the Friedmann equations, and matter is…
The original Kerr theorem provides the foundation for Kerr-Schild transformations by classifying all shear-free and geodesic null congruences in flat spacetime; the key ingredient of the Kerr-Schild ansatz. However, due to the high level of…
We consider a modified Brans-Dicke theory in which except the usual Brans-Dicke parameter a new dimensionful parameter appears which modifies the kinetic term of the scalar field coupled to gravity. Solving the coupled Einstein-Klein-Gordon…
As is well-known, Kerr-Schild metrics linearize the Einstein tensor. We shall see here that they also simplify the Gauss-Bonnet tensor, which turns out to be only quadratic in the arbitrary Kerr-Schild function f when the seed metric is…
We construct black hole solutions with spin-induced scalarization in a class of models where a scalar field is quadratically coupled to the topological Gauss-Bonnet term. Starting from the tachyonically unstable Kerr solutions, we obtain…
A pair of wave equations for the electromagnetic and gravitational perturbations of the charged Kerr black hole are derived. The perturbed Einstein-Maxwell equations in a new gauge are employed in the derivation. The wave equations refer to…
We present exact solutions to the Einstein-Maxwell system of equations in spherically symmetric gravitational fields with a specified form of the electric field intensity. The condition of pressure isotropy yields a difference equation with…
The wormhole solution could be found by solving the Einstein field equations with violating the null energy condition (NEC). We represent wormhole solutions in $\kappa(R,T)$ gravity in two different ways. At first, we find the shape…
The separated radial part of a massive complex scalar wave equation in the Kerr- Sen geometry is shown to satisfy the generalized spheroidal wave equation which is, in fact, a confluent Heun equation up to a multiplier. The Hawking…
This paper invokes a new mechanism for reducing a coupled system of fields (including Einstein's equations without a cosmological constant) to equations that possess solutions exhibiting characteristics of immediate relevance to current…
The resolution of the nonlinear stability of black holes as solutions to the Einstein equations relies crucially on imposing the right geometric gauge conditions. In the vacuum case, the use of Generally Covariant Modulated (GCM) spheres…
It is now widely accepted that the universe as we understand it is accelerating in expansion and fits the de Sitter model rather well. As such, a realistic assumption of black holes must place them on a de Sitter background and not…
The massless conformally coupled scalar field is characterized by the so-called "new improved stress-energy tensor", which is capable of classically violating the null energy condition. When coupled to Einstein gravity we find a…
The KP hierarchy is a completely integrable system of quadratic, partial differential equations that generalizes the KdV hierarchy. A linear combination of Schur functions is a solution to the KP hierarchy if and only if its coefficients…
In this paper, we study some of the properties of the $G \to 0$ limit of the Kerr-Newman solution of Einstein-Maxwell equations. Noting Carter's observation of the near equality between the $g = 2$ gyromagnetic ratio in the Kerr-Newman…
Besides scalarized black holes and wormholes, Einstein-scalar-Gauss-Bonnet theories allow also for particle-like solutions. The scalar field of these particle-like solutions diverges at the origin, akin to the divergence of the Coulomb…