On axis orphan afterglows are afterglows with no preceding γ-ray emission that arise within the initial GRB jet. This could happen if the GRB and afterglow emission are beamed differently in different wavelengths, as would be the case if the relativistic Lorentz factors varies strongly with angle within GRB jets. We show that the observations of the WFC on BeppoSAX constrain with high certainty...

We propose an ultrafast all-optical technique to control and beam the light emerging from a sub-wavelength slit in a planar gold film by exciting a transient grating in the area around the slit. A FDTD model is used to show how excitation of surface plasmon polaritons by the grating governs the beaming process. Both the grating and the beaming effect are shown to decay on a picosecond time-scal...

We consider a gamma-ray burst (GRB) model based on an anisotropic fireball with an axisymmetric energy distribution of the form ǫ(θ) ∝ θ, and allow for the observer’s viewing direction being at an arbitrary angle θv with respect to the jet axis. This model can reproduce the key features expected from the conventional on-axis uniform jet models, with the novelty that the achromatic break time in...

One ingredient in an empirical birthrate estimate for pulsar binaries is the fraction of sky subtended by the pulsar beam: the pulsar beaming fraction. This fraction depends on both the pulsar’s opening angle and the misalignment angle between its spin and magnetic axes. The current estimates for pulsar binary birthrates are based on an average value of beaming fractions for only two pulsars, i...

Extreme accretion in X-ray pulsars (XRPs) results radiation-driven outflows launched from the inner parts of disc. The affect apparent luminosity XRPs and their pulsations through geometrical beaming. We model processes beaming pulse formation using Monte Carlo simulations. confirm our earlier statement that strong amplification due to collimation photons is inconsistent with a large pulsed fra...

— Gamma-Ray Bursts (GRBs) are widely thought to originate from collimated jets of material moving at relativistic velocities. Emission from such a jet should be visible even when viewed from outside the angle of collimation. Using Monte Carlo population synthesis methods and including the effects of this off-axis beaming, we can compare various GRB jet models against the global properties of ob...

The degree of beaming in Gamma-Ray Bursts (GRBs) is currently unknown. The uncertainty in the γ-ray beaming angle, θb, leaves the total energy release (∝ θ2 b) and the event rate per galaxy (∝ θ b ) unknown to within orders of magnitude. Since the delayed radio emission of GRB sources originates from a mildly relativistic shock and receives only weak relativistic beaming, the rate of radio-sele...

Beaming of relativistic ejecta in GRBs has been postulated by many authors in order to reduce the total GRB energy, thus it is very important to look for the observational evidence of beaming. Rhoads (1999) has pointed out that the dynamics of the blast wave, which is formed when the beamed ejecta sweeping the external medium, will be significantly modified by the sideways expansion due to the ...