On the causal characterization of singularities in spherically symmetric spacetimes

The causal character of the zero-areal-radius (R = 0) singularity in spherically symmetric spacetimes is studied. By using the techniques of the qualitative behaviour of dynamic systems, we are able to present the most comprehensive scheme so far to try to find out their causal characterization, taking into account and analysing, the possible limitations of the approach. We show that, with this approach, the knowledge of the scalar invariant m = R(1 - g(mu nu)partial derivative(mu)R partial derivative(nu)R)/2 suffices to characterize the singularity. We apply our results to the study of the outcome of black hole evaporation and show different possibilities. In this way, we find that a persistent naked singularity could develop in the final stages of the evaporation and we show its distinctive features. Likewise, we study the options for the generation of naked singularities in the collapse of an object (such as a star) as a means of violating the cosmic censorship conjecture.