Pure Gauss–Bonnet NUT black hole with and without non-central singularity

It is known that NUT solution has many interesting features and pathologies like being non-singular and having closed timelike curves. It turns out that in higher dimensions horizon topology cannot be spherical but it has instead to be product of 2-spheres so as to retain radial symmetry of spacetime. In this letter we wish to present a new solution of pure Gauss–Bonnet $$\Lambda $$ Λ -vacuum equation describing a black hole with NUT charge. It has three interesting cases: (a) black hole with both event and cosmological horizons with singularity being hidden behind the former, (b) a regular spacetime free of both horizon and singularity, and (c) black hole with event horizon without singularity and cosmological horizon. Singularity here is always non-centric at $$r \ne 0$$ r ≠ 0 .

Effect of Quench Severity and Hardness of Aluminium 2585 Alloyusing Eco Friendly Quenchants

Rate of cooling, hardness and severity during quenching of various media viz; cow urine, distilled water, tap water, engine oil (unused) SAE40 soap nut solution, shikakai nut solution for industrial heat treatment was investigated using 2585 Al alloy. For all media, nucleate boiling and convective heat transfer are being carried out and out of which maximum and minimum cooling rates are observed for cow urine. From the study it has been observed that cow urine, tap water and distilled water, cow urine has high heat transfer coefficient 6.577W/m2K, whereas Engine oil, Shikakai nut solution, Soap nut solution are considered Soap nut solution has high heat transfer coefficient 3.654 W/m2K. For all the quenchants, the hardness of Al 2585 alloy increased cow urine

CFT duals on extremal rotating NUT black holes

We investigate the Kerr–Newman–NUT black hole solution obtained from Plebański–Demiański solutions with several assumptions. The origin of the microscopic entropy of this black hole is investigated using the conjectured Kerr/CFT correspondence which is originally proposed for extremal Kerr black holes. The isometry of the near-horizon extremal Kerr–Newman–NUT black hole shows that the asymptotic symmetry group may be implemented to compute the central charge of the Virasoro algebra. Furthermore, by assuming the Frolov–Thorne vacuum, the conformal temperatures can be obtained. Then by using the Cardy formula, the microscopic entropy is gained which matches the Bekenstein–Hawking entropy. We also employ the Cardy prescription to find the logarithmic correction of the entropy. Then at limit [Formula: see text], the extremal Reissner–Nordström–NUT solution is recovered and by enhancing with the fibered coordinate we find the five-dimensional (5D) solution. The second dual CFT is applied to this black hole to gain the entropy. Finally, the microscopic entropy is still in agreement with the area law of 5D black hole solution. Hence, the extremal Reissner–Nordström–NUT solution is holographically dual to the CFT.

ROTATING RELATIVISTIC THIN DISKS AS SOURCES OF CHARGED AND MAGNETIZED KERR–NUT SPACE–TIMES

A family of models of counterrotating and rotating relativistic thin disks of infinite extension based on a charged and magnetized Kerr–NUT metric are constructed using the well-known "displace, cut and reflect" method extended to solutions to vacuum Einstein–Maxwell equations. The metric considered has as limiting cases a charged and magnetized Taub–NUT solution and the well-known Kerr–Newman solutions. We show that for Kerr–Newman fields the eigenvalues of the energy–momentum tensor of the disk are for all the values of the parameters' real quantities so that these disks do not present heat flow in any case, whereas for charged and magnetized Kerr–NUT and Taub–NUT fields we always find regions with heat flow. We also find a general constraint on the counterrotating tangential velocities needed to cast the surface energy–momentum tensor of the disk as the superposition of two counterrotating charged dust fluids. We show that, in general, it is not possible to take the two counterrotating fluids as circulating along electrogeodesics or take the two counterrotating tangential velocities as equal and opposite.