87 research outputs found
Helicity-Rotation-Gravity Coupling for Gravitational Waves
The consequences of spin-rotation-gravity coupling are worked out for linear
gravitational waves. The coupling of helicity of the wave with the rotation of
a gravitational-wave antenna is investigated and the resulting modifications in
the Doppler effect and aberration are pointed out for incident high-frequency
gravitational radiation. Extending these results to the case of a
gravitomagnetic field via the gravitational Larmor theorem, the rotation of
linear polarization of gravitational radiation propagating in the field of a
rotating mass is studied. It is shown that in this case the linear polarization
state rotates by twice the Skrotskii angle as a consequence of the spin-2
character of linear gravitational waves.Comment: 11 pages, no figures, accepted for publication in Phys. Rev. D; v2: a
few minor typos correcte
Gravitational deflection of light and helicity asymmetry
The helicity modification of light polarization which is induced by the
gravitational deflection from a classical heavy rotating body, like a star or a
planet, is considered. The expression of the helicity asymmetry is derived;
this asymmetry signals the gravitationally induced spin transfer from the
rotating body to the scattered photons.Comment: 6 pages, 1 figur
Global and local perspectives of gravitationally assisted negative-phase-velocity propagation of electromagnetic waves in vacuum
Consistently with the Einstein equivalence principle and using an
electromagnetic formulation first suggested by Tamm, we show that a local
observer cannot observe negative-phase-velocity (NPV) propagation of
electromagnetic waves in vacuum, whereas a global observer can appreciate that
phenomenon. Using the specific example of the Kerr metric, we also demonstrate
the possibility of NPV propagation within the ergosphere of a rotating black
hole
Optics of spin-1 particles from gravity-induced phases
The Maxwell and Maxwell-de Rham equations can be solved exactly to first
order in an external gravitational field. The gravitational background induces
phases in the wave functions of spin-1 particles. These phases yield the optics
of the particles without requiring any thin lens approximation.Comment: 16 pages, 2 figure
Towards gravitationally assisted negative refraction of light by vacuum
Propagation of electromagnetic plane waves in some directions in
gravitationally affected vacuum over limited ranges of spacetime can be such
that the phase velocity vector casts a negative projection on the time-averaged
Poynting vector. This conclusion suggests, inter alia, gravitationally assisted
negative refraction by vacuum.Comment: 6 page
Superradiation from Crystals of High-Spin Molecular Nanomagnets
Phenomenological theory of superradiation from crystals of high-spin
molecules is suggested. We show that radiation friction can cause a
superradiation pulse and investigate the role of magnetic anisotropy, external
magnetic field and dipole-dipole interactions. Depending on the contribution of
all these factors at low temperature, several regimes of magnetization of
crystal sample are described. Very fast switch of magnetization's direction for
some sets of parameters is predicted.Comment: 10 pages, 3 figure
Propagation of Light in the Field of Stationary and Radiative Gravitational Multipoles
Extremely high precision of near-future radio/optical interferometric
observatories like SKA, Gaia, SIM and the unparalleled sensitivity of LIGO/LISA
gravitational-wave detectors demands more deep theoretical treatment of
relativistic effects in the propagation of electromagnetic signals through
variable gravitational fields of the solar system, oscillating and precessing
neutron stars, coalescing binary systems, exploding supernova, and colliding
galaxies. Especially important for future gravitational-wave observatories is
the problem of propagation of light rays in the field of multipolar
gravitational waves emitted by a localized source of gravitational radiation.
Present paper suggests physically-adequate and consistent mathematical solution
of this problem in the first post-Minkowskian approximation of General
Relativity which accounts for all time-dependent multipole moments of an
isolated astronomical system.Comment: 36 pages, no figure
Gravitomagnetic Effects in the Propagation of Electromagnetic Waves in Variable Gravitational Fields of Arbitrary-Moving and Spinning Bodies
Propagation of light in the gravitational field of self-gravitating spinning
bodies moving with arbitrary velocities is discussed. The gravitational field
is assumed to be "weak" everywhere. Equations of motion of a light ray are
solved in the first post-Minkowskian approximation that is linear with respect
to the universal gravitational constant . We do not restrict ourselves with
the approximation of gravitational lens so that the solution of light geodesics
is applicable for arbitrary locations of source of light and observer. This
formalism is applied for studying corrections to the Shapiro time delay in
binary pulsars caused by the rotation of pulsar and its companion. We also
derive the correction to the light deflection angle caused by rotation of
gravitating bodies in the solar system (Sun, planets) or a gravitational lens.
The gravitational shift of frequency due to the combined translational and
rotational motions of light-ray-deflecting bodies is analyzed as well. We give
a general derivation of the formula describing the relativistic rotation of the
plane of polarization of electromagnetic waves (Skrotskii effect). This formula
is valid for arbitrary translational and rotational motion of gravitating
bodies and greatly extends the results of previous researchers. Finally, we
discuss the Skrotskii effect for gravitational waves emitted by localized
sources such as a binary system. The theoretical results of this paper can be
applied for studying various relativistic effects in microarcsecond space
astrometry and developing corresponding algorithms for data processing in space
astrometric missions such as FAME, SIM, and GAIA.Comment: 36 pages, 1 figure, submitted to Phys. Rev.
Spacetime Splitting, Admissible Coordinates and Causality
To confront relativity theory with observation, it is necessary to split
spacetime into its temporal and spatial components. The (1+3) timelike
threading approach involves restrictions on the gravitational potentials
, while the (3+1) spacelike slicing approach involves
restrictions on . These latter coordinate conditions protect
chronology within any such coordinate patch. While the threading coordinate
conditions can be naturally integrated into the structure of Lorentzian
geometry and constitute the standard coordinate conditions in general
relativity, this circumstance does not extend to the slicing coordinate
conditions. We explore the influence of chronology violation on wave motion. In
particular, we consider the propagation of radiation parallel to the rotation
axis of stationary G\"odel-type universes characterized by parameters and such that for ) chronology is
protected (violated). We show that in the WKB approximation such waves can
freely propagate only when chronology is protected.Comment: 25 pages, 3 figures; v2: minor typos corrected, accepted for
publication in Phys. Rev.
Gravitomagnetism in the Kerr-Newman-Taub-NUT spacetime
We study the motion of test particles and electromagnetic waves in the
Kerr-Newman-Taub-NUT spacetime in order to elucidate some of the effects
associated with the gravitomagnetic monopole moment of the source. In
particular, we determine in the linear approximation the contribution of this
monopole to the gravitational time delay and the rotation of the plane of the
polarization of electromagnetic waves. Moreover, we consider "spherical" orbits
of uncharged test particles in the Kerr-Taub-NUT spacetime and discuss the
modification of the Wilkins orbits due to the presence of the gravitomagnetic
monopole.Comment: 12 pages LaTeX iopart style, uses PicTex for 1 Figur
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