In general relativity, the spacetimes of black holes have three fundamental properties: (i) they are same, to lowest order in spin, as metrics stellar objects; (ii) independent mass when expressed geometric units; and (iii) described by Kerr metric. this paper, we quantify upper bounds on potential black-hole metric deviations imposed observations shadows binary inspirals explore current experi...

We construct a model for the formation of black holes within galactic bulges. The initial state is a slowly rotating isothermal sphere, characterized by effective transport speed aeff and rotation rate Ω. The black hole mass is determined when the centrifugal radius of the collapse flow exceeds the capture radius of the central black hole. This model reproduces the observed correlation between ...

It has been argued that a black hole horizon can support the long range fields of a Nielsen-Olesen string, and that one can think of such a vortex as black hole “hair”. In this paper, we examine the properties of an Abelian Higgs vortex in the presence of a charged black hole as we allow the hole to approach extremality. Using both analytical and numerical techniques, we show that the magnetic ...

We derive the theoretical distribution function of black hole masses by studying the formation processes of black holes. We use the results of recent 2D simulations of core-collapse to obtain the relation between remnant and progenitor masses and fold it with an initial mass function for the progenitors. We examine how the calculated black-hole mass distributions are modified by (i) strong wind...

The universality of Martinez’s conjecture, which states that the quasilocal energy of a black hole at the outer horizon reduces to twice its irreducible mass, or equivalently, to √ A/4π (A is the area of the black hole), is investigated by calculating Brown-York quasilocal energies for stationary black holes in heterotic string theory, e. g., for the stationary Kaluza-Klein black hole, the rota...

The universality of Martinez’s conjecture, which states that quasilocal energy of a black hole at the outer horizon reduces to twice its irreducible mass, or equivalently, to √ A/4π (A is the area of the black hole), is investigated by calculating Brown-York quasilocal energies for stationary black holes in heterotic string theory, such as for the stationary Kaluza-Klein black hole, the rotatin...

Motivated by the recent interest on models with varying constants and whether black hole physics can constrain such theories, two-dimensional charged stringy black holes are considered. We exploit the role of two-dimensional stringy black holes as toy models for exploring paradoxes which may lead to constrains on a theory. A two-dimensional charged stringy black hole is investigated in two diff...

Black-hole physics mirrors thermodynamics in many respects. Inparticular, it is widely believed that a system consisting of ordinary matter interacting with a black hole will obey the generalized second law of thermodynamics. In this paper we challenge the validity of the law in a gedanken experiment in which an entropy-bearing rotating system falls into a stationary black hole. It is shown tha...

We derive and discuss black–hole solutions to the gravitating O(3) σ model in (2+1) dimensions. Three different kinds of static black holes are found. One of these resembles the static BTZ black hole, another is completely free of singularities, and the last type has the same Penrose diagram as the (3+1)–dimensional Schwarzschild black hole. We also construct static and dynamical multi–black ho...

or Does the 2D black hole have tachyonic or W–hair? Abstract We solve the equations of motion of the tachyon and the discrete states in the background of Witten's semiclassical black hole and in the exact 2D dilaton-graviton background of Dijkgraaf et al. We find the exact solutions for weak fields, leading to conclusions in disagreement with previous studies of tachyons in the black hole. Dema...