The external field of a rotating and charged body in the vector graviton metric theory

We discuss certain properties of the external field of a rotating and charged body in the frame of the vector graviton metric field theory. We find: 1) a black hole cannot have angular momentum or charge, that is, a rotating body whether charged or not, cannot be a black hole. The Kerr black hole and the Kerr-Newman black hole do not exist. 2) For a rotating and charged axisymmetric body, there exists a latitude-dependent critical distance r_k(θ), such that the radial force acting on a test particle is attractive or repulsive according as the particle is outside or inside the critical distance. The repulsive force means that a massive object cannot collapse indefinitely. Maximum redshift in this case comes from sources on the equator. 3) A test particle also experiences a force along the meridian.     

Corrected Hawking radiation from a charged rotating black string

Using the Damour–Ruffini method, Hawking radiation from a four-dimensional charged rotating black string in asymptotically anti-de Sitter space–time is investigated. When energy, angular momentum, charge conservations, and the particles’ back-reaction to the space–time are taken into account, the exact emission spectrum near the horizon is calculated. The horizon is not spherical, but can be toroidal and cylindrical. Our results indicate that the spectrum is not purely thermal, which may be consistent with an underlying unitary theory. Moreover, it is a possible mechanism to explain the information loss paradox.     

Density distortion within a rotating body

This paper ascertains the distortion of the density distribution within a self-gravitating body in hydrostatic equilibrium under the influence of rotation.For this purpose, the Poisson equation has been solved by using the undistorted density profile _o(a) within the Laplacian to obtain the distorted density (a, ). The Laplacian has been expressed in terms of a system of curvilinear coordinates for which the equipotential surfaces constitute a family of fundamental surfaces.In performing the requisite algebraic manipulations, the Clairaut and Radau equations developed in a previous paper (Lanzano, 1974) were utilized to eliminate the derivatives of the elements pertaining to the equipotential surfaces.The density distortion has been obtained up to third-order terms in a small rotational parameter.     

Thermodynamics of charged and rotating black strings

We study thermodynamics of cylindrically symmetric black holes. Uncharged as well as charged and rotating objects have been discussed. We derive surface gravity and hence the Hawking temperature and entropy for all these cases. We correct some results in the literature and present new ones. It is seen that thermodynamically these black configurations behave differently from spherically symmetric objects.     

The charged particle in the magnetosphere of a rotating neutron star

The motion of charged particles in a pulsar magnetosphere is examined in the present paper. Using the non-relativistic approximation, the trajectories of the charged particles are investigated qualitativley both in the case of axial and in the case of incline rotator. The obtained results can be used for the construction of the pulsar magnetosphere.     

The equilibrium of a rotating body of arbitrary density

This paper extends Clairaut's theory of rotational equilibrium to third order terms in a small parameter and is meant to be a sequel to a 1962 publication by the author bearing on the same topic. It has been feasible to obtain the Clairaut equation, which governs the deformation of the equipotential surfaces within a rapidly rotating mass in hydrostatic equilibrium, as an ordinary differential equation. This has been achieved by eliminating the two integral terms which appeared in the original formulation. It is expected that the numerical integration of this newly obtained equation will contribute toward a more precise solution of certain geophysical problems — e.g., the determination of the geoid to an accuracy of ±1 m, and the correction to the travel-time of seismic waves; it should also assist in some planetary questions like the determination of the exterior shape for the rapidly rotating planets Jupiter and Saturn.     

Chaotic gravitational zones around a regularly shaped complex rotating body

In preparation for the Rosetta mission, the location and widths of gravitational resonances surrounding a regularly shaped and possibly complex rotating body are mapped following the second fundamental model of resonance. It is found that for uniaxial rotation of the central body, the surrounding resonances are widest for prograde orbits. If the figure axis is tilted with respect to the spin axis of the central body, an additional number of wide resonances appear with a preference for prograde and inclined orbits, and the occurrence of initial conditions which lie in the globally connected chaotic web is significantly increased. For larger rotational excitations, it is seen how these new additional resonances overlap internally at low eccentricity for very large semi-major axes. However, with exceptions for some excited short-axis rotational modes of the central body, it is argued that most resonances vanish for retrograde orbits lying in the plane normal to the body spin, and that resonant or non-resonant stability therefore can be expected for a wide range of mean orbit eccentricities.     

The multipolar structure of the gravitational radiation from a rotating body

We give the metric coefficients of the retarded field of non-plane gravitational waves from a multipolar source at infinity, and hence the expression for the power of the multipole radiation from a slowly rotating body. When specific calculations are made for the quadrupole radiation, we find that the radiation from a rotating body has a strong directivity. Our calculated results for the total power of two pulsars are in good agreement with previous estimates.     

On the motion of a mass point inside a rotating inhomogeneous ellipsoidal body

The plane motion of a mass point inside an inhomogeneous rotating ellipsoidal body with a homothetic density distribution is considered. The force function of the problem is expanded in terms of the ellipsoid's second eccentricities up to the fourth order, which are taken as small parameters. We derive an expression for the perturbing function and solve the equations of perturbed motion in orbital elements.     

Wall temperature oscillation on convection flow in a rotating fluid with hall and ion-slip currents

An analysis of Hall and ion-slip current effects on the MHD free-convection flow of a partiallyionised gas past an infinite vertical porous plate in a rotating frame of reference is carried out. A strong magnetic field is applied perpendicular to the plate and the plate temperature oscillates in time about a constant non-zero mean. The problem has been solved for the velocity and temperature fields and the effects of _e (the Hall parameter), _i (the ion-slip parameter),E _r (rotation parameter), and have been discussed and shown graphically.     

A new model of angular momentum transfer from the rotating central body of a two‐body system to the orbital motion of the system

In a previous paper we treated within the framework of our Projective Unified Field Theory (Schmutzer 2004, 2005a) the 2‐body system (e.g. Earth‐Moon system) with a rotating central body in a rather abstract manner. Here a concrete model of the transfer of angular momentum from the rotating central body to the orbital motion of the whole 2‐body system is presented, where particularly the transfer is caused by the inhomogeneous gravitational force of the Moon acting on the oceanic waters of the Earth, being modeled by a spherical shell around the solid Earth. The theory is numerically tested. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gravitational instability of a rotating plasma

The gravitational instability of an infinite homogeneous self-gravitating rotating plasma in the presence of a uniform vertical magnetic field has been studied to include the FLR effects. It has been found that the Jeans' criterion of instability remains unaffected even if rotation and FLR effects are included. The effect of rotation is to decrease the Larmor radius by an amount-depending upon the wavenumber of perturbation. The particular cases of the effect of FLR and rotation on the waves propagated along and perpendicular to the magnetic field have been discussed.     

Gravitational collapse of a charged viscous-fluid universe

In the course of obtaining three collapsing models of the charged viscous-fluid distribution, the dynamics of gravitational collapse are investigated with respect to them, and their physical and geometrical properties are studied critically, In all the cases, with a proper choice of the mass, the interior solution can be matched to the exterior Schwarzschild vacuum solution, thereby the solution being continuous at the boundary of the star. In all these models the matter inside is found to be radiating thus giving us the opportunity of identifying the gravitational collapse of a realistic astrophysical object. At the boundary of these model stars the matter distribution comes out to be that of dust and thereby comoving with respect to the coordinate system used. All the models are seen to be physically acceptable; they come out to be realistic models of collapsing astrophysical objects which will be of much interest in studying the phenomenon of black holes in this Universe.     

Corrected Hawking temperature of Warped AdS3 rotating Black Hole by using tunneling method

In this paper, we have calculated the corrected Hawking temperature for the Warped AdS₃ rotating Black Hole by using the tunneling method beyond the semi-classical approximation for the Warped AdS₃ rotating Black Hole. For this purpose, we have isolated the r-t sector of the metric from the angular part throughout a coordinate transformation near the horizon.     

Two‐body system with a rotating central body (e.g. Earth‐Moon system) within the Projective Unified Field Theory

In this treatise the well‐known 2‐body problem with a rotating central body is systematically reinvestigated on the basis of the Projective Unified Field Theory (PUFT) under the following aspects (including the special case of the Newton mechanics): First, equation of motion with abstract additional terms being appropriate for the interpretation of the various effects under discussion: tidal friction effect as well as non‐tidal effects (e.g. rebound effect as temporal variation of the moment of inertia of the rotating body, general‐relativistic Lense‐Thirring effect, new scalaric effects of cosmological origin, being an outcome of the scalarity phenomenon of matter (PUFT). Second, numerical evaluation of the theory. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)