相关论文: The Averaged Null Energy Condition and the Black H…

The potential behind the horizon of an eternal black hole in classical theories is described in terms of data that is available to an external observer -- the reflection coefficient of a wave that scatters on the black hole. In GR and…

We show that negative $(\nabla \Phi)^2$, where $\Phi$ is the dilaton, leads to a rapid creation of folded strings. Consequently it appears that the interior of the $SL(2,\mathbb{R})_k/U(1)$ black hole is not empty, but is filled with folded…

We find all the classical solutions (minimal surfaces) of open or closed strings in {\it any} two dimensional curved spacetime. As examples we consider the SL(2,R)/R two dimensional black hole, and any 4D black hole in the Schwarzschild…

The energy condition inequalities for the matter stress energy comprised out of the dilaton and Maxwell fields in the dilaton-Maxwell gravity theories emerging out of string theory are examined in detail. In the simplistic 1+1 dimensional…

The coupling of a string to gravity allows for Schwarzschild black holes whose entropy to area relation is $S=(A/4)(1-4\mu)$, where $\mu$ is the string tension. This departure from the A/4 universality results from a string instanton…

We establish the relationship between the space-time structure of regular spherically-symmetrical black holes and the character of violation of the strong energy condition (SEC). It is shown that it is violated in any static region under…

A new identity reported here for the first time is used for studying how the null energy condition can be applied to the models of dynamical black holes proposed recently [I. I. Cot\u aescu, Eur. Phys. J. C (2022) 82:86]. It is shown that…

Equations of motion of null cosmic strings near black holes, or other massive sources, are solved exactly in the weak field approximation. The stress-energy tensor of a null string in a curved spacetime is introduced and used to show how…

A general principle of statistical mechanics is that low energy excitations of a thermal state change expectation values of observables by a very small amount. However some observables in the vicinity of the horizon of a large black hole in…

We argue that classical $(\alpha')$ effects qualitatively modify the structure of Euclidean black hole horizons in string theory. While low energy modes experience the geometry familiar from general relativity, high energy ones see a rather…

This manuscript investigates a Schwarzschild black hole surrounded by perfect fluid dark matter embedded in a cloud of strings. The effects of its surroundings on thermodynamics, timelike and null geodesics, shadows, and quasinormal modes…

The leading classical low-energy effective actions for two-dimensional string theories have solutions describing the gravitational collapse of shells of matter into a black hole. It is shown that string loop corrections can be made…

We investigate the properties of a class of near-extreme static black hole solutions called naked black holes. These black holes, which occur in string theory, have small curvature invariants but large tidal forces outside their event…

We evaluate the probability that a loop of string that has spontaneously nucleated during inflation will form a black hole upon collapse, after the end of inflation. We then use the observational bounds on the density of primordial black…

The new, rapidly developing field of theoretical research --- studies of dark energy interacting with black holes (and, in particular, accreting onto black holes) --- is reviewed. The term `dark energy' is meant to cover a wide range of…

String theory provides an example of the kind of apparent inconsistency that the {\it Principle of Black Hole Complementarity\/} deals with. To a freely infalling observer a string falling through a black hole horizon appears to be a Planck…

We study the possible black string-black hole transition by analyzing the structure of the apparent horizon for a large family of time-symmetric initial data. We observe that, as judged by the apparent horizon, it is possible to generate…

We revisit the geometry representing l collinear Schwarzschild black holes. It is seen that the black holes' horizons are deformed by their mutual gravitational attraction. The geometry has a string like conical singularity that connects…

An interesting case of string/black hole transition occurs in two-dimensional non-critical string theory dressed with a compact CFT. In these models the high energy densities of states of perturbative strings and black holes have the same…

$U(1)$ zero modes in the $SL(2,R)_k/U(1)$ and $SU(2)_k/U(1)$ conformal coset theories, are investigated in conjunction with the string black hole solution. The angular variable in the Euclidean version, is found to have a double set of…