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The gravitational collapse of a star is an important issue both for general relativity and astrophysics, which is related to the well known frozen star paradox. Following the seminal work of Oppenheimer and Schneider (1939), we present the exact solution for two dust shells collapsing towards a pre-existing black hole. We find that the inner region of the shell is influenced by the property of the shell, which is contrary to the result in Newtonian theory and and the clock inside the shell becomes slower as the shell collapses towards the pre-existing black hole. This result in principle may be tested experimentally if a beam of light travels across the shell. We conclude that the concept of the frozen star should be abandoned, since matter can indeed cross a black holes horizon according to the clock of an external observer. Since matter will not accumulate around the event horizon of a black hole, we predict that only gravitational wave radiation can be produced in the final stage of the merging process of two coalescing black holes. Our results also indicate that for the clock of an external observer, matter, after crossing the event horizon, will never arrive at the singularity (i.e. the exact center of the black hole.
Exact solutions describing rotating black holes can offer important tests for alternative theories of gravity, motivated by the dark energy and dark matter problems. We present an analytic rotating black hole solution for a class of vector-tensor the
We address the question of the uniqueness of the Schwarzschild black hole by considering the following question: How many meaningful solutions of the Einstein equations exist that agree with the Schwarzschild solution (with a fixed mass m) everywhere
The first fully integrated explicit exact solution of the Einstein field equations corresponding to the superposition of a counterrotating dust disk with a central black hole is presented. The obtained solution represents an infinite annular thin dis
One of the problems in the current asymptotic symmetry would be to extend the black hole to the rotating one. Therefore, in this paper, we obtain a four-dimensional asymptotically flat rotating black hole solution including the supertraslation corrections.
Primordial black holes could have been formed in the early universe from non linear cosmological perturbations re-entering the cosmological horizon when the Universe was still radiation dominated. Starting from the shape of the power spectrum on supe