Related papers: Diverse Jet Structures Consistent with the Off-axi…
Gamma-ray burst (GRB) afterglows are well described by synchrotron emission originating from the interaction between a relativistic blast wave and the external medium surrounding the GRB progenitor. We introduce a code to reconstruct…
Gamma-Ray Burst (GRB) afterglows arise from the interaction of relativistic ejecta with the circumburst medium and are observed across the electromagnetic spectrum. Afterglow polarisation is expected at early and late phases depending on…
The afterglow of GRB$\,$170817A/GW$\,$170817 was very unusual, slowly rising as $F_\nu\propto{}t_{\rm{}obs}^{0.8}\nu^{-0.6}$, peaking at $t_{\rm{obs,pk}}\sim\,150\;$days, and sharply decaying as $\sim{}t_{\rm{}obs}^{-2.2}$. VLBI…
To date GW170817, produced by a binary neutron star (BNS) merger, is the only gravitational wave event with an electromagnetic (EM) counterpart. It was associated with a prompt short gamma-ray burst (GRB), an optical kilonova, and the…
Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow…
We present general analytic expressions for GRB afterglow light curves arising from a variable external density profile and/or a variable energy in the blast wave. The former could arise from a clumpy ISM or a variable stellar wind; The…
Gamma-ray burst (GRB) prompt emission is highly beamed, and understanding the jet geometry and beaming configuration can provide information on the poorly understood central engine and circum-burst environment. Prior to the advent of…
A two-component jet model is proposed to explain the unusual afterglow of GRB 070419A. Regarding the optical light curve, a wide "jet" with an opening angle of > 30-40 degrees is assumed to produce the late shallow decay, while the three…
The recent discovery of a faint gamma-ray burst (GRB) coincident with the gravitational wave (GW) event GW 170817 revealed the existence of a population of low-luminosity short duration gamma-ray transients produced by neutron star mergers…
The origin of GRBs have been a mystery for almost 30 years. The afterglow observed in the last few years enabled redshift determination for a handful of bursts, and the cosmological origin is now firmly established. Though the distance…
The two leading interpretations of achromatic breaks that are observed in the light curves of GRBs afterglow are (i) the manifestation of the edge of a jet, which has a roughly uniform energy profile and a sharp edge and (ii) a line of…
We test the spectral-energy correlation including the new bursts detected (mostly) by Swift with firm measurements of their redshifts and peak energy. The problem of identifying the jet breaks is discussed in the complex and…
We carry out a numerical hydrodynamical modeling for the evolution of a relativistic collimated outflow, as it interacts with the surrounding medium, and calculate the light-curve resulting from synchrotron emission of the shocked fluid.…
We have performed detailed calculations of spectra and light curves of GRB afterglows assuming that the observed GRBs can have a jet geometry. The calculations are based on an expanding relativistic shock GRB afterglow model where the…
The steepening (break) of the power-law fall-off observed in the optical emission of some GRB afterglows at epoch ~1 day is often attributed to a collimated outflow (jet), undergoing lateral spreading. Wider opening GRB ejecta with a…
Particle acceleration is expected to be different between relativistic and non-relativistic collisionless shocks. We show that electromagnetic counterparts to gravitational waves (GWs), gamma-ray burst (GRB) afterglows, are ideal targets…
Early rebrightenings at a post-burst time of 10^2 - 10^4 s have been observed in the afterglows of some gamma-ray bursts (GRBs). Unlike X-ray flares, these rebrightenings usually last for a relatively long period. The continuous energy…
We present Ulysses and NEAR data from the detection of the short or intermediate duration (2 s) gamma-ray burst GRB000301C (2000 March 1.41 UT). The gamma-ray burst (GRB) was localised by the Inter Planetary Network (IPN) and RXTE to an…
The TeV afterglow of the BOAT GRB 221009A was interpreted as arising from a narrow jet while the radio to X-ray afterglows were interpreted as arising from a wide structured jet. However, there is no model explaining the TeV and…
The afterglows to gamma-ray bursts (GRBs) are due to synchrotron emission from shocks generated as an ultra-relativistic outflow decelerates. A forward and a reverse shock will form, however, where emission from the forward shock is well…