A Kerr black hole can flare quasi-periodically, if it is magnetically connected to the accretion disk. The flares extract the rotational energy of the hole. The flaring occurs because the hole twists the magnetic field lines beyond the threshold of the screw instability. Subject headings: black holes – magnetic fields

We show that in general holographic stress tensor may contain a new term of divergence of a spacelike unit normal acceleration. Then, it is shown that in contrast to previous descriptions, a new stress tensor for Kerr-AdS solutions can be a traceless one. Interestingly, this prescription entails a local failure on the IR-UV connection.

We derive constraints on the form of the renormalized stress tensor for states on Kerr space-time based on general physical principles: symmetry, the conservation equations, the trace anomaly and regularity on (sections of) the event horizon. This is then applied to the physical vacua of interest. We introduce the concept of past and future Boulware vacua and discuss the non-existence of a stat...

For Schwarzschild space-time, distributional expressions of energy-momentum densities and of scalar concomitants of the curvature tensors are examined for a class of coordinate systems which includes those of the Schwarzschild and of Kerr-Schild types as special cases. The energy-momentum density e T (x) of the grav-itational source and the gravitational energy-momentum pseudo-tensor density e ...

We construct a supersymmetric rotating black hole with asymptotically flat four-dimensional spacetime times a circle, by superposing an infinite number of BMPV black hole solutions at the same distance in one direction. The near horizon structure is the same as that of the five-dimensional BMPV black hole. The rotation of this black hole can exceed the Kerr bound in general relativity (q ≡ a/G4...

The beam quality parameter Mx for self-phase modulated Gaussian and super-Gaussian beams has been calculated analytically. These results can be used for experimental measurements of nonlinearities in optical materials. A super-Gaussian beam with a size comparable to a Gaussian one demonstrates much more stable behavior with propagation through Kerr media. The deteriorated beam quality parameter...

1 Department of Civil Engineering, Faculty of Engineering, Prince of Songkla University, Songkhla 90112, Thailand 2 Civil Engineering Program, School of Engineering, University of Phayao, Phayao 5600, Thailand 3Department of Civil Engineering, ERI, Gyeongsang National University, Jinju 660-701, Republic of Korea 4Department of Civil Engineering, Gangneung-Wonju National University, Gangneung 21...

In this article we study the pointwise decay properties of solutions to the wave equation on a class of stationary asymptotically flat backgrounds in three space dimensions. Under the assumption that uniform energy bounds and a weak form of local energy decay hold forward in time we establish a t−3 local uniform decay rate for linear waves. This work was motivated by open problems concerning de...

Time dispersion plays an important role in the propagation of femtosecond pulses through water. The combined e ects of time dispersion, radial di raction and the Kerr nonlinearity on the pulse propagation are analyzed and it is shown that normal time dispersion leads to signi cant temporal broadening of ultrashort pulses and that it increases the threshold power for catastrophic self-focusing.