English

Can gravitational collapse sustain singularity-free trapped surfaces?

General Relativity and Quantum Cosmology 2008-11-26 v1 Astrophysics High Energy Physics - Theory

Abstract

In singularity generating spacetimes both the out-going and in-going expansions of null geodesic congruences θ+\theta ^{+} and θ\theta ^{-} should become increasingly negative without bound, inside the horizon. This behavior leads to geodetic incompleteness which in turn predicts the existence of a singularity. In this work we inquire on whether, in gravitational collapse, spacetime can sustain singularity-free trapped surfaces, in the sense that such a spacetime remains geodetically complete. As a test case, we consider a well known solution of the Einstien Field Equations which is Schwarzschild-like at large distances and consists of a fluid with a p=ρp=-\rho equation of state near r=0r=0. By following both the expansion parameters θ+\theta ^{+} and θ\theta ^{-} across the horizon and into the black hole we find that both θ+\theta ^{+} and θ+θ\theta ^{+}\theta ^{-} have turning points inside the trapped region. Further, we find that deep inside the black hole there is a region 0r<r00\leq r<r_{0} (that includes the black hole center) which is not trapped. Thus the trapped region is bounded both from outside and inside. The spacetime is geodetically complete, a result which violates a condition for singularity formation. It is inferred that in general if gravitational collapse were to proceed with a p=ρp=-\rho fluid formation, the resulting black hole may be singularity-free.

Keywords

Cite

@article{arxiv.0708.2360,
  title  = {Can gravitational collapse sustain singularity-free trapped surfaces?},
  author = {Manasse R. Mbonye and Demosthenes Kazanas},
  journal= {arXiv preprint arXiv:0708.2360},
  year   = {2008}
}

Comments

17 pages, 3 figures, accepted for publication in International Journal of Modern Physics D

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