Because of the corotation, the polarization angle (PA) curve of a pulsar lags the intensity profile by 4r/Rlc rad in pulse phase. I present a simple and short derivation of this delay-radius relation to show that it is not caused by the aberration (understood as the normal beaming effect) but purely by contribution of corotation to the electron acceleration in the observer’s frame. Available al...

Based on the refined dynamical model proposed by us earlier for beamed γ-ray burst ejecta, we carry out detailed numerical procedure to study those γray bursts with rapidly fading afterglows (i.e., ∼ t). It is found that optical afterglows from GRB 970228, 980326, 980519, 990123, 990510 and 991208 can be satisfactorily fitted if the γ-ray burst ejecta are highly collimated, with a universal ini...

The detection of x-ray afterglows of gamma-ray burst (GRB) sources has enabled the optical discovery that GRBs are at cosmological distances, which confirms that the enormous luminosities required must produce a relativistically expanding fireball. It is not yet clear if this expansion is quasi-spherical or beamed, or if the beaming differs between the prompt GRB and afterglow, although the dif...

Nature succeeds in accelerating extended and massive objects to relativistic velocities. Jets in Active Galactic Nuclei and in galactic superluminal sources and gamma–ray bursts fireballs have bulk Lorentz factors from a few to several hundreds. A variety of effects then arises, such as the beaming of the produced radiation, light aberration, time contraction and the Doppler frequency shift. I ...

There are now a half dozen young pulsars detected in high energy photons by the Compton GRO, showing a variety of emission efficiencies and pulse profiles. We present here a calculation of the pattern of high energy emission on the sky in a model which posits γ-ray production by charge depleted gaps in the outer magnetosphere. This model accounts for the radio to γ-ray pulse offsets of the know...

The realization that the relativistic outflow in GRBs is in the form of jets has direct implication to their energy budget and their rates. This has, in turn, further implications on the nature of the inner engine. For example prior to the understanding that GRBs are beamed, events such as GRB 990123 with an isotropic equivalent energy of more than 10 erg were hard to explain. With beaming the ...

Internal shocks propagating through an ambient radiation field, are subject to a radiative drag that, under certain conditions, can significantly affect their dynamics and, consequently, the evolution of the beaming cone of emission produced behind the shocks. The resultant change of the Doppler factor combined with opacity effects leads to a strong dependence of the variability pattern produce...

We model the intermediate time evolution of a “jetted” gamma-ray burst by two blobs of matter colliding with the interstellar medium. We follow the hydrodynamical evolution of this system numerically and calculate the bremsstrahlung and synchrotron images of the remnant. We find that for a burst energy of 10 erg the remnant becomes spherical after ∼ 5000 years when it collects ∼ 50M⊙ of interst...