This work is devoted to the mathematical study of the Hawking effect for fermions in the setting of the collapse of a rotating charged star. We show that an observer who is located far away from the star and at rest with respect to the Boyer Lindquist coordinates observes the emergence of a thermal state when his proper time goes to infinity. We first introduce a model of the collapse of the st...

In axistationary, asymptotically flat spacetimes, zero angular momentum observers (ZAMOs) define an absolute standard of non-rotation locally, as can be verified by the absence any Sagnac effect for these observers. Nevertheless, we argue that on a global scale only physically meaningful concept is relative rotation. The argument substantiated solving Einstein’s equations approximate thin shell...

Rigidly rotating stationary matter in general relativity has been investigated by Kramer (Class. Quantum Grav. 2 L135 (1985)) by the Ernst coordinate method. A weakness of this approach is that the Ernst potential does not exist for differential rotation. We now generalize the techniques by the use of a nonholonomic and nonrigid frame. We apply these techniques for differentially rotating perfe...

We show that the onion-to-vortex switching field in dense arrays of nanostructured ferromagnetic rings is strongly dependent on the angle between the applied magnetic field and the array’s main axis. The variations in switching field of up to 8 mT are connected to the anisotropy produced by dipolar interactions between domain walls in the rings. The interactions stabilize the onion state in ali...

We analyze the energy extraction by the Penrose process in higher dimensions. Our result shows the efficiency of the process from higher dimensional black holes and black rings can be rather high compared with than that in four dimensional Kerr black hole. In particular, if one rotation parameter vanishes, the maximum efficiency becomes infinitely large because the angular momentum is not bound...

Dynamics of relativistic outflows along the rotation axis of a Kerr black hole is investigated using a simple model and the evolution of the speed of the flow relative to the ambient medium is studied. We assume that a flow clump is under the influence of the relativistic tidal force of the central source as well as the Lorentz force due to the large-scale electromagnetic field that is assumed ...

We interpret the cosmological constant as energy of vacuum, and under a minimum amount assumptions, we show that it is deformed in vicinity black hole. This leads us to reexamine Kerr-de Sitter solution. provide new solution, simpler geometrically richer, which shows impact rotation form warped curvature. carry out detailed exact study on hole conclude with conjecture regarding possible our res...