Cosmic censorship, massless fermionic test fields, and absorption probabilities

Abstract

In the conventional approach, fermionic test fields lead to a generic overspinning of black holes resulting in the formation of naked singularities. The absorption of the fermionic test fields with arbitrarily low frequencies is allowed for which the contribution to the angular momentum parameter of the spacetime diverges. Recently we have suggested a more subtle treatment of the problem considering the fact that only the fraction of the test fields that is absorbed by the black hole contributes to the space-time parameters. Here, we re-consider the interaction of massless spin (1/2) fields with Kerr and Kerr-Newman black holes, adapting this new approach. We show that the drastic divergence problem disappears when one incorporates the absorption probabilities. Still, there exists a range of parameters for the test fields that can lead to overspinning. We employ backreaction effects due to the self-energy of the test fields which fixes the overspinning problem for fields with relatively large amplitudes, and renders it non-generic for smaller amplitudes. This non-generic overspinning appears likely to be fixed by alternative semi-classical and quantum effects.

Destroying Kaluza-Klein and Kerr-Newman black holes

“…The similar idea to Hubeny's in violating WCCC for Kerr black hole was proposed Jacobson and Sotiriou [9], for Kerr-Newman black hole were discussed in [10,11], and for magnetized Kerr black hole is investigated in [12]. The reconsideration of WCCC in the fashion of Hubeny [8] is not limited just to black holes in Einstein-Maxwell theory, but also beyond [13,14,15,16,17,18,19,20]. However, a newer version of checking WCCC by Sorce and Wald [21] shows that if the self-force and finite size effects are considered, then no such black hole destruction as illustrated in [8,9,11,12] can occur.…”

Challenging cosmic censorship in Einstein-Maxwell-scalar theory with numerically simulated gedanken experiments

“…Within general relativity (GR) a particularly relevant series of gedanken experiments is devoted to test Penrose's cosmic censorship conjecture, according to which in four spacetime dimensions naked singularities (i.e., curvature singularities not covered by an event horizon) cannot form from typical regular initial data (see [2] for an overview and a list of historical references). This conjecture has been put to the test by trying to overcharge/overspin a black hole (BH) past extremality, by throwing test particles [3][4][5][6][7][8][9], shells of matter [4], fluids [10], test fields [9,[11][12][13], etc. Indeed, charged (respectively, spinning) BHs in GR have a maximum amount of charge (respectively, angular momentum) in units of their mass and above a critical value the Reissner-Nordström (RN) (respectively, Kerr) solution describes a naked singularity.…”

Challenging the cosmic censorship in Einstein-Maxwell-scalar theory with numerically simulated gedankenexperiments

“…curvature singularities not covered by an event horizon) cannot form from typical regular initial data (see [2] for an overview and a list of historical references). This conjecture has been put to the test by trying to overcharge/overspin a black hole (BH) past extremality, by throwing test particles [3][4][5][6][7][8][9], shells of matter [4], fluids [10], test fields [9,11], etc. Indeed, charged (resp., spinning) BHs in GR have a maximum amount of charge (resp., angular momentum) in units of their mass and above a critical value the Reissner-Nordström (RN) (resp., Kerr) solution describes a naked singularity.…”