Related papers: No space-time singularity in black-hole physics
A definition of a Newtonian black hole is possible which incorporates the mass-energy equivalence from special relativity. However, exploiting a double spherical shell model, it will be shown that the ensuing gravitational self-energy and…
We construct a static spherically symmetric regular black hole with a Minkowski core, and a degenerate inner horizon with vanishing surface gravity. The spacetime contains a non-extremal outer horizon and exhibits two notable features.…
Black hole spacetimes are semiclassically not static. For black holes whose lifetime is larger than the age of the universe we compute, in leading order, the power spectrum of deviations of the electromagnetic charge from it's average…
An exact solution representing black holes in an expanding universe is found. The black holes are maximally charged and the universe is expanding with arbitrary equation of state. It is an exact solution of the Einstein-scalar-Maxwell…
A non-singular black hole solution is briefly presented which violates energy conditions only at its interior by postulating a consistent shift to negative energies and gravitationally repulsive negative masses at the event horizon. This…
The horizon (the surface) of a black hole is a null surface, defined by those hypothetical "outgoing" light rays that just hover under the influence of the strong gravity at the surface. Because the light rays are orthogonal to the spatial…
The "no hair" theorem is not applicable to black holes formed from collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that…
We contrast the evolution of gravitational binary mergers for the two cases of a black hole and a normal neutron star, and a black hole and a self-bound strange quark matter star. In both cases inspiral continues until the Roche limit is…
We track the evolution of entropy and black holes in a cyclic universe that undergoes repeated intervals of expansion followed by slow contraction and a smooth (non-singular) bounce. In this kind of cyclic scenario, there is no big crunch…
We study the dynamics of a pair of extremal (half-BPS) black holes in $\mathcal{N}=8$ supergravity, as a potentially solvable model of gravitational dynamics. As a diagnosis of hidden symmetries, we ask whether the perihelion of the orbits…
The definition of matter states on spacelike hypersurfaces of a 1+1 dimensional black hole spacetime is considered. Because of small quantum fluctuations in the mass of the black hole, the usual approximation of treating the gravitational…
We describe black holes in d+3 dimensions, whose thermodynamic properties correspond to those of a scale invariant non-relativistic d+1 dimensional quantum system with dynamical exponent z=2. The gravitational model involves a massive…
In the standard viewpoint, the temperature of a stationary black hole is proportional to its surface gravity, $T_H=\hbar\kappa/2\pi$. This is a semiclassical result and the quantum gravity effects are not taken into consideration. This…
Particle collisions are considered within the context of $f(R)$ gravity described by $f(R)=R+2\alpha\sqrt{R}$, where $R$ stands for the Ricci scalar and $\alpha$ is a non-zero constant. The center of mass (CM) energy of head-on colliding…
We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius $r_{core}\approx…
A field-theoretic model for a highly compact object that mimicks a black hole is found for the gravitationally interacting system of a boson star and a global monopole which are nonminimally coupled to gravity. According to the strength of…
The mergers of black hole-neutron star binaries are calcuated using a pseudo-general relativistic potential that incorporates ${\mathcal O}(v^2/c^2)^3$ post-Newtonian corrections. Both normal matter neutron stars and self-bound strange…
It is a common wisdom that properties of macroscopic bodies are well described by (semi)classical physics. As we have suggested this wisdom is not applicable to black holes. Despite being macroscopic, black holes are quantum objects. They…
Explicitly covariant analytical expressions are derived that describe the boundaries of shadows cast by massive particles scattered by a gravitating object. This covers scenarios with particles having effectively variable mass, such as…
Is the graviton massless? This problem was addressed in the literature at a phenomenological level, using modified dispersion relations for gravitational waves, in linearized calculations around flat space. Here, we perform a detailed…