In this work, we generalized the Kerr-Newman-NUT black hole solution in Rastall gravity from Ref. 1. Here we are more focused on the black hole dynamics such as the event horizons, ergosurface, ZAMO, thermodynamic properties, and the equatorial circular orbit around the black hole such as static radius limit, null equatorial circular orbit, and innermost stable circular orbit. We present how the NUT and Rastall parameter affects the dynamic of the black hole.
In recent years, the classical version of the null energy condition (NEC) has been enhanced into its quantum generalization, the quantum null energy condition (QNEC). The right-hand side of the QNEC inequality is non-zero; it is multiplied by a factor of ћ and recovers the standard NEC in the classical limit. Moreover, the second derivative of entanglement entropy also plays a role in determining the right-hand side. In this work, we study several examples of theories of inflation that violate the standard NEC, yet still, possibly obey the QNEC. This suggests that the deviation of the standard NEC arises due to the existence of entanglement between regions inside and outside of the cosmological horizon. Possible connection to quantum fluctuations of de Sitter spacetime is also studied.
We calculate the entanglement entropy between two (maximally-extended) spacetime regions of static black hole, separated by horizon. As a first case, we consider the Schwarzschild black hole, and then we extend the calculations to the charged Reissner–Nordström and Schwarzschild–de Sitter black holes with more than one horizon. The case for static and spherically-symmetric solution to the more general [Formula: see text] gravity is also considered. The calculation of the entanglement entropy is performed using the replica trick by obtaining the explicit form of the metric which corresponds to the replica spacetime for each black hole under consideration. The calculation of static and spherically-symmetric black holes results in the entanglement entropy that matches the Bekenstein–Hawking area law entropy.
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