Physics Letters B (Aug 2020)
Area (or entropy) products for Newman-Unti-Tamburino class of black holes
Abstract
We compute area (or entropy) product formula for Newman-Unti-Tamburino (NUT) class of black holes. Specifically, we derive the area product of outer horizon and inner horizon (H±) for Taub-NUT, Euclidean Taub-NUT black hole, Reissner-Nordström–Taub-NUT black hole, Kerr-Taub-NUT black hole and Kerr-Newman-Taub-NUT black hole under the formalism developed very recently by Wu et al. (2019) [1]. The formalism is that a generic four dimensional Taub-NUT spacetime should be described completely in terms of three or four different types of thermodynamic hairs. They are defined as the Komar mass (M=m), the angular momentum (Jn=mn), the gravitomagnetic charge (N=n), the dual (magnetic) mass (M˜=n). After incorporating this formalism, we show that the area (or entropy) product of both the horizons for NUT class of black holes are mass-independent. Consequently, the area product of H± for these black holes are universal. Which was previously known in the literature that the area product of said black holes are mass-dependent. Finally, we can say that this universality is solely due to the presence of new conserved charges JN=MN which is closely analogue to the Kerr like angular momentum J=aM.
