Testing cosmic censorship conjecture near extremal black holes with cosmological constants

Understand

It has been shown previously that an extremal Reissner-Nordstr\"om or an extremal Kerr black hole cannot be overcharged or overspun by a test particle if radiative and self-force effects are neglected.

• In this paper, we consider extremal charged and rotating black holes with cosmological constants.
• By studying the motion of test particles, we find the following results: An extremal Reissner-Nordstr\"om anti-de Sitter (RN-AdS) black hole can be overcharged by a test particle but an extremal Reissner-Nordstr\"om de Sitter (RN-dS) black hole cannot be overcharged.
• We also show that both extrmal Kerr-de-Sitter (Kerr-dS) and Kerr-anti-de-Sitter (Kerr-AdS) black holes can be overspun by a test particle, implying a possible breakdown of the cosmic censorship conjecture.