Frame-dragging Research Articles

Slow rotation of radiating viscous-fluid Universe coupled with scalar field

Investigations are being made on slowly rotating models of radiating viscous fluid coupled with scalar field in spherically-symmetric Einstein Universe, and some new analytic solutions are found to substantiate the possibility of the existence of such universes. The nature and role of the rotational velocity Ω(r, t) which is related to the local dragging of inertial frames and that of matter rotation ω(r, t) are studied. We also discuss the effects of the radiation field and the scalar field on the rotation. Rotating models which are expanding are obtained, where in all the cases the rotational velocities are found to decay with the time; and these models may be taken as good examples of real astrophysical situations.

Dragging of inertial frames by the rotating Earth: Proposal and feasibility for a ground-based detection

We are proposing a ground-based experiment to detect the Lense-Thirring drag due to the rotating earth by an off-line comparison between an astrometric measurement of the Earth rotation and an inertial measurement of the angular velocity of the laboratory. It is shown that the former, by means of routine observations of Very Long Baseline Interferometry, has already reached the accuracy needed to perform a 3 % experiment on a time span of ∼1 yr. We propose to perform the latter by a dynamical detector of local rotation of novel conception, the Gyromagnetic Electron Gyroscope. Its principle of operation is briefly discussed together with its response to rotationlike gravitational fields.

Slow rotational perturbations of Robertson-Walker universes

A slow rotation perturbation of Robertson-Walker universes filled with perfect fluid has been investigated. It is found that the unit-four vector of perfect fluid hasno angular velocity in the perturbed cosmological models. The slow rotation which is related to the dragging of the local inertial frames, is compatible only with the cases of positive and negative curvatures of the cosmological universe. The intrinsic velocity vector field of the Universe isexpanding as well asshearing.

Inhomogeneous cosmology. III - Primordial gravitational waves and dust

In this paper, the properties of a special class of inhomogeneous cosmological models and the interaction of the inhomogeneities with the evolution of the background geometry and matter are studied. The cosmological model is chosen so that the initial inhomogeneities evolve into 'plane' gravitational waves propagating through a smooth Bianchi I dust background. It is shown how the inhomogeneities interact with matter, 3 K radiation, and the background geometry, causing the expansion to slow down in some regions and speed up in others. It is also shown how the gravitational waves can produce a 'dragging of the inertial frame' which will affect the observed distribution of matter and 3 K radiation. In particular, this frame-dragging effect can account for a major fraction of the obsserved dipole component between the 3 K background radiation and the rest frame of global matter, an effect usually assumed to have been produced by large-scale local motion.

On the maximum mass of a uniformly rotating neutron star

The effect of rapid uniform rotation on the upper mass limit for neutron stars is studied under the assumption that the equation of state is subject to only a minimal set of physical constraints. For given ranges of the energy condition, microstability constraint, and causality constraint, the maximum mass of a uniformly rotating neutron star is about 24-25 percent greater than the corresponding nonrotating maximum mass. The obtained value is compared with that of the maximum mass of uniformly rotating configurations associated with the stiffest of the equations of state proposed for actual neutron-star matter. Rotation increases the upper limit on baryon mass by only about 20 percent, while the limiting moment of inertia is about twice its value for the nonrotating case. Upper limits are also found for the frequency of rotation, the frequency of frame dragging, and the maximum polar and equatorial redshifts. Discarding the causality constraint would allow the upper mass limit to increase by a given value. 16 references.

Rotational perturbations of cosmological viscous-fluid Universe with zero-mass scalar field

Certain new analytic solutions for the rotational perturbations of the Robertson-Walker universe are found out to substantiate the possibility of the existence of a rotating viscous universe with zero-mass scalar field. The values for Ω(r, t) which is related to the local dragging of inertial frames are investigated. In all the cases the rotational velocity is found to decay with time. Except for ‘perfect dragging’ the scalar field is found to have a damping effect on the rotation of matter. The damping effect is found to be roughly analogous to viscosity. In some solutions it is found that the scalar field may exist only during a time period in the course of evolution of the Universe.

Slowly-rotating cosmological perfect fluids

The Einstein field equations for a perfect fluid distribution representing slowly-rotating fluid spheres are investigated. By imposing restrictions on the matter rotation ω(r, t) which is related to the dragging of inertial frames, and a uniform rotation which is a function of time, the general solutions for Ω(r, t) are obtained for all cosmological models. In the case of closed models the solutions for Ω(r, t) may represent realistic astrophysical situations only when the radial distance is greater than −1 and less than +1.

A mass shell with flat interior cannot rotate rigidly

Previous work on approximate solutions for rotating mass shells with flat interior is extended to third order in the angular velocity omega . It is shown that the condition of flatness can only be preserved in this order if the mass shell exhibits differential rotation. The first-order result, that a compact rotating mass shell with M=2R creates total dragging of the inertial frames inside the shell, is not invalidated by third-order corrections. By analysing the structure of the solutions in arbitrary order of omega , it is proven that there exists exactly one solution for a rotating mass shell with flat interior.

Slow rotation of compressible viscous fluid in cosmological universe

New analytic solutions for rotational perturbations of the Robertson-Walker metric are found in order to incorporate the possibility of a rotating viscous universe. The field equations impose restrictions on the matter rotationω(r, t), and some of the solutions for Ω(r, t) which is related to the local dragging of inertial frames are studied. In all the cases the rotational velocity is found to decay with increase of time. Geodesics of the metric are studied to reveal the intrinsic nature of rotation and to elucidate the role of Ω.

General relativistic effects on the pulse profile of fast pulsars

The recent discovery of millisecond pulsars1,2 has led to several theories about the structure3–8 and radiation characteristics9–11 of rapidly rotating neutron stars. The rapid rotation rate implies that such pulsars will be compact5 (implying large space-time curvature) and that surface emission characteristics will differ significantly from the non-rotational (Schwarzchild) case11. We report here the implications of large space-time curvature and large rotation (specifically, the dragging of inertial frames introduced by rotation) on the trajectories of photons, and hence, on the pulse profile of fast pulsars. Space-time curvature leads to substantial amounts of divergence in the pulse width and reduction in the pulse intensity whereas rotation produces a tilt of the pulse cone from its original direction of emission, and deforms the cone, introducing an asymmetry in the (flattened) pulse profile leading to a time delay in the arrival of photons emitted within the pulse cone. We find that the effect of curvature dominates over that of rotation, suggesting a larger brightness temperature than inferred observationally for all pulsars whatever the rotation rate (unless the pulsar is of very low mass).

Charge, magnetic dipole, and lense-thirring effect in the generalized theory of gravitation

Three physical problems are solved in the framework of the generalized theory of gravitation. The gravitational field of a point charged mass and an expression for the vector potential for a magnetic field of dipole nature are found, and the angular velocity of frame dragging by the rotation of a central body is calculated.

Foucault Pendulum at the South Pole: Proposal For an Experiment to Detect the Earth's General Relativistic Gravitomagnetic Field

An experiment is proposed for measuring the earth's gravitomagnetic field by monitoring its effect on the plane of swing of a Foucault pendulum at the south pole ("dragging of inertial frames by earth's rotation"). With great effort a 10% experiment in a measurement time of several months might be achieved.

Near zero, a frontier of physics

By reducing several of the variables of physics, such as temperature, electric field, magnetic field, gravitational field, and electric charge, very nearly to zero, new regions of physics can be explored. This makes possible the investigation of many fundamental problems in physics such as the dragging of inertial frames in general relativity; the search for gravitational waves from collapsing stars; the search for fraction electric charge on matter; the search for monopoles; the force of gravity on electrons and positrons; the electric dipole moment on 3He; the equivalence principle; a more accurate determination of the λ transition in zero gravitational field; the search for a new gravitational particle by checking the inverse square law of gravity; and the measurement of fundamental constants h/m, α.

Near zero, a frontier of physics

By reducing several of the variables of physics, such as temperature, electric field, magnetic field, gravitational field, and electric charge, very nearly to zero, new regions of physics can be explored. This makes possible the investigation of many fundamental problems in physics such as the dragging of inertial frames in general relativity; the search for gravitational waves from collapsing stars; the search for fraction electric charge on matter; the search for monopoles; the force of gravity on electrons and positrons; the electric dipole moment on 3 He; the equivalence principle; a more accurate determination of the λ transition in zero gravitational field; the search for a new gravitational particle by checking the inverse square law of gravity; and the measurement of fundamental constants h/m , α.

The Tolman-Wyman equation in general relativity

Abstract We show that the equation depicting inertial frame dragging for a slowly rotating fluid is the homogeneous part of the Tolman-Wyman equation. Hence, expressions for the dragging of inertial frames can be obtained from knowledge of a complete solution to the Tolman-Wyman equation. Two examples are given.

Inertial frames determined from the rotational laws observed in spiral galaxies

In 1976, the author deduced from the observed circular velocities within the Galactic System that the upper limit of the angular velocity of the inertial frames with respect to the reference coordinate system of positional astronomy is of the order of 10 −3 arcsec/century (Horák, 1976). In the present paper the circular velocities observed in four other spiral galaxies are investigated in order to obtain analogous limits also for the projections of the relative angular velocity of the mentioned coordinate systems on axes of rotation of the galaxies considered. It is shown that the special relativistic effects as well as the general relativistic Thirring's effect on the inertial frames can be neglected. It turns out that the probable upper limit of the relative rotation rate of the local inertial frames around the axes of the spiral galaxies M 31, NGC 2146, M 81 and NGC 5055 is of the order of 10 −3–10 −2 acrsec/century. Since the galaxies investigated are rotating around axes oriented differently in space, one can conclude that the inertial frames do not practically rotate with respect to the reference system of positional astronomy around any axis. This conclusion is of importance for the general theory of relativity as well as for the navigation and guidance of a starship.

Charged particle orbits in Kerr geometry with electromagnetic fields as viewed from locally non-rotating frames

The charged particle orbits in electromagnetic fields on Kerr background as viewed from a locally non-rotating frame do not exhibit non-gyrating bound orbits, which was an essential feature in the earlier study of Prasanna and Vishveshwara, thus showing the non gyration to be due to the effect of dragging of inertial frames produced by the rotating black hole.

Time, length, and mass changes in a gravitational field

Seen from afar, time dilates, rulers contract, and masses increase in the induced field inside either a hollow accelerating cylinder or the equivalent GM r 2 field. Frame dragging causes these effects to be due to velocity when viewed close at hand.

Slow rotation in the bimetric theory of gravitation

The equations describing the moment of inertia and the dragging of inertial frames of slowly rotating neutron stars are derived according to Rosen's bimetric theory of gravitation. Numerical calculations of the properties of neutron stars according to the bimetric theory and general relativity were made using several equations of state. The general trend found is that in the bimetric theory neutron stars with a given mass induce a smaller dragging of inertial frames than in general relativity. The moment of inertia of low-mass stars also is smaller in the bimetric theory. For high-mass stars, however, the moment of inertia is found to be larger in the bimetric theory.

Slowly rotating, relativistic stars

view Abstract Citations (6) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Slowly rotating, relativistic stars. Abramowicz, M. A. ; Wagoner, R. V. Abstract The paper presents an analytic theory of slowly and uniformly rotating, general relativistic bodies, (neutron stars) which is based on Bardeen's variational principle. Analytic formulas for the total mass, total angular momentum, total baryon number, moment of inertia, and the angular velocity of the dragging of inertial frames are obtained. Analytic formulas are also derived for the rotational corrections to various physical quantities. These results indicate that the maximum mass of a stable neutron star in which the speed of sound is less than c can be increased by at most about 20% due to rotation. Publication: The Astrophysical Journal Pub Date: December 1978 DOI: 10.1086/156683 Bibcode: 1978ApJ...226.1063A Keywords: Dynamic Models; Neutron Stars; Relativity; Stellar Models; Stellar Rotation; Angular Momentum; Density (Mass/Volume); Gravitation Theory; Stellar Mass; Variational Principles; Astrophysics; Masses:Neutron Stars; Relativistic Stars:Rotation full text sources ADS |