Related papers: Backscattering: an overlooked effect of General Re…
The observation by the BATSE instrument on the Compton Gamma Ray Observatory that gamma-ray bursts (GRBs) are distributed isotropically around the Earth but nonuniformly in distance has led to the widespread conclusion that GRBs are most…
We revisit the gravitational lensing phenomenon using a new visualization technique. It consists in projecting the observers sky into the source plane, what gives rise to a folded and stretched surface. This provides a clear graphical tool…
It is shown that the light scattered by a finite 2D crystal strip in the region of an exciton resonance should display strong backscattering. This phenomenon is related to the exciton reflection from the edge of the strip.
We analyze the scalar radiation emitted from a source rotating around a Schwarzschild black hole using the framework of quantum field theory at the tree level. We show that for relativistic circular orbits the emitted power is about 20% to…
If the background universe is observed through a significant amount of diffusely distributed foreground dust, then studies at optical wavelengths may be severely biased. Previous studies investigating effects of foreground dust on…
The propagation of $\gamma$ rays over very large distances provides new insights on the intergalactic medium and on fundamental physics. On their path to the Earth, $\gamma$ rays can annihilate with diffuse infrared or optical photons of…
Coherent backscattering is a coherence effect in the propagation of waves through disordered media involving two or more scattering events. Here, we report on the observation of coherent backscattering from individual atoms and their mirror…
This paper proposes a strategy for detecting the presence of a gravito-magnetic field due to the rotation of the galactic dark halo. Visible matter in galaxies rotates and dark matter, supposed to form a halo incorporating barionic matter,…
Future lensing surveys will be nearly full-sky and reach an unprecedented depth, probing scales closer and closer to the Hubble radius. This motivates the study of the cosmic shear beyond the small-angle approximation and including general…
Recent data suggest that the Universe could be positively curved. Combined with an inflationary stage, this might lead to a curvature bounce instead of the Big Bang. The background evolution is presented, as a function of the parameters…
We find that in general relativity slow down of the pulsar rotation due to the magnetodipolar radiation is more faster for the strange star with comparison to that for the neutron star of the same mass. Comparison with astrophysical…
The paradox of a free falling radiating charged particle in a gravitational field, is a well-known fascinating conceptual challenge that involves classical electrodynamics and general relativity. We discuss this paradox considering the…
The kinematical effect induced by the transversal motion of a gravitational lens on the frequency shift of light has been investigated in detail, while the effect of the radial motion is thought to be much smaller than the transversal one…
Gravitational waves can act like gravitational lenses, affecting the observed positions, brightnesses, and redshifts of distant objects. Exact expressions for such effects are derived here in general relativity, allowing for…
The effect of gravitational microlensing on the intensity of gravitational radiation as it propagates through an inhomogeneous medium containing small-scale structure is considered. Lensing by both stars and a power law spectrum of density…
It has recently become apparent that the background level of diffuse radio emission on the sky is significantly higher than the level that can result from known extragalactic radio source classes or our Galaxy given our current…
We consider a new set of effects arising from the quantum gravity corrections to the propagation of fields, associated with fluctuations of the spacetime geometry. Using already existing experimental data, we can put bounds on these effects…
We study gravitational lensing when plasma surrounds the lens. An extra deflection angle is induced by the plasma in addition to the deflection generated by gravity. An inhomogeneous plasma distribution generates a greater effect than a…
The observed flat rotation curves of galaxies require either the presence of dark matter in Newtonian gravitational potentials or a significant modification to the theory of gravity at galactic scales. Detecting relativistic Doppler shifts…
Inverse Compton scattering by relativistic electrons produces a major component of the diffuse emission from the Galaxy. The photon fields involved are the cosmic microwave background and the interstellar radiation field from stars and…