Destroying Extremal Kerr-Newman-AdS Black Holes with Test Particles

Neglecting the self-force, self-energy and radiative effects, we follow the spirit of Wald＇s gedanken experiment and further discuss whether an extremal Kerr-Newman-AdS （KNA） black hole can turn into a naked singularity when it captures charged and spinning massive particles. It is found that feeding a test particle into an extremal KNA black hole could lead to a violation of cosmic censorship for the black hole.

Weak gravity conjecture from conformal field theory:a challenge from hyperscaling violating and Kerr-Newman-AdS black holes

We search for a possible relationship between weak gravity conjecture(WGC)and conformal field theory(CFT)in hyperscaling violating and Kerr-Newman-AdS black holes.We deal with the critical points of the black hole systems using the correlation function introduced in CFT and discuss WGC conditions using the imaginary part of the energy obtained from the critical points and their poles.Under the assumptions z=1,d=1,andθ→0-,we link WGC to hyperscaling violating black holes owing to the existence of rHvalues larger and smaller than one.For the second black hole system,we study the conditions of WGC for Kerr-Newman-AdS black holes using rotation and radius parameters.Then,we show that the conditions of WGC are satisfied when the charged particle near the hyperscaling violating and Kerr-Newman black holes is 1/a with a ratio a/l《1.

Nonexistence of time-periodic solutions of the Dirac equation in non-extreme Kerr-Newman-AdS spacetime

In non-extreme Kerr-Newman-Ad S spacetime, we prove that there is no nontrivial Dirac particle which is Lpfor 0 < p≤ 4/3 with arbitrary eigenvalue λ, and for 4/3< p≤ 4/(3-2q), 0 < q <3/2 with eigenvalue|λ| > |Q| + qκ, outside and away from the event horizon. By taking q =1/2, we show that there is no normalizable massive Dirac particle with mass greater than |Q| +κ/2 outside and away from the event horizon in non-extreme Kerr-Newman-Ad S spacetime, and they must either disappear into the black hole or escape to infinity, and this recovers the same result of Belgiorno and Cacciatori in the case of Q = 0 obtained by using spectral methods.Furthermore, we prove that any Dirac particle with eigenvalue |λ| <κ/2 must be L^2 outside and away from the event horizon.

Destroying a Near-Extremal Kerr-Newman-AdS Black Hole with Test Particles

If radiative and self-force effects are neglected, we find that feeding a test particle into a near-extremal Kerr- Newman-AdS black hole could lead to destroy their event horizon, giving rise to naked singularities. Hence radiative and self-force effects must be taken into account to further test cosmic censorship. Moreover, the allowed paxameter range for this test particle is very narrow, this leaves the possibility of radiative and self-force effects considerations to cure the problem of WCC violation in Kerr-Newman-AdS spacetime.