Related papers: Reverse Shock Emission as a Probe of GRB Ejecta
The deviation from the power-law decline of the optical flux observed in GRB 970228 and GRB 980326 has been used recently to argue in favor of the connection between GRBs and supernovae. We consider an alternative explanation for this…
In the standard scenario of the fireball model of gamma-ray bursts(GRBs), the huge initial energy release produces a relativistic blast wave expanding into the external medium and a reverse shock moving into and heating the fireball ejecta.…
Early afterglow observations of gamma-ray bursts (GRBs) are valuable for exploring the properties of their jets and ambient medium. We report our photometric and spectroscopic observations of GRB 210104A and discuss its jet properties with…
We study the morphology of gamma-ray burst (GRB) afterglows viewed off-axis using a simplified analytical model. We consider steep jets, which are expected to be the most common type. These jets, characterized by steep lateral gradients in…
The Gamma-Ray Burst (GRB) 021211 detected by the High Energy Transient Explorer (HETE) II had a simple light-curve in the x-ray and gamma-ray energy bands containing one peak and little temporal fluctuation other than the expected Poisson…
Beamed gamma-ray burst (GRB) sources produce a bow shock in their gaseous environment. The emitted flux from this bow shock may dominate over the direct emission from the jet for lines of sight which are outside the angular radius of the…
Recently, GRB 221009A, known as the brightest of all time (BOAT), has been observed across an astounding range of $\sim 18$ orders of magnitude in energy, spanning from radio to VHE bands. Notably, the Large High Altitude Air Shower…
Internal shocks are a leading candidate for the dissipation mechanism that powers the prompt $\gamma$-ray emission in gamma-ray bursts (GRBs). In this scenario a compact central source produces an ultra-relativistic outflow with varying…
In this work, we present the results obtained from a multi-wavelength campaign, as well as from the public Swift/BAT, XRT, and UVOT data of GRB 060111B for which a bright optical emission was measured with good temporal resolution during…
Gamma-ray bursts (GRBs) are emitted by relativistic ejecta from powerful cosmic explosions. Their light curves suggest that the gamma-ray emission occurs at early stages of the ejecta expansion, well before it decelerates in the ambient…
The detection of the hyper-bright gamma-ray burst (GRB) 221009A enables us to explore the nature of GRB emission and the origin of very-high-energy (VHE) gamma-rays. We analyze the ${\it Fermi}$-LAT data and investigate GeV-TeV emission in…
In the popular internal shock model for the prompt emission of gamma-ray bursts (GRBs), collisions between a series of relativistic shells generate lots of paired forward and reverse shocks. We show that the synchrotron emission produced by…
Fast ejecta expelled in binary neutron star (NS) mergers or energetic supernovae (SNe) should produce late-time synchrotron radio emission as the ejecta shocks into the surrounding ambient medium. Models for such radio flares typically…
X-ray emission can provide a crucial diagnostic of gamma-ray bursts (GRBs). We calculate the X-ray and gamma-ray spectra of impulsive acceleration episodes related to GRB pulses. We use the synchrotron shock model (SSM) as a basis of our…
Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space- and…
In the past two years, tremendous progresses to understand X-ray Flashes have been made. Now it is widely believed that X-ray Flashes and Gamma-ray Bursts are intrinsically the same, their much different peak energy and flux may be just due…
The prompt optical emission of GRB 990123 was uncorrelated to the gamma-ray light-curve and exhibited temporal properties similar to those of the steeply-decaying, early X-ray emission observed by Swift at the end of many bursts. These…
The optical light-curves of GRB afterglows 990123 and 021211 exhibit a steep decay at 100--600 seconds after the burst, the decay becoming slower after about 10 minutes. We investigate two scenarios for the fast decaying early optical…
As it was recently shown by Derishev etal (1999), initial GRB ejecta are likely to contain comparable number of protons and neutrons. During acceleration process, and/or later, due to interaction with external medium, such ejecta are likely…
We propose to explain the recent observations of GRB early X-ray afterglows with SWIFT by the dissipation of energy in the reverse shock which crosses the ejecta as it is decelerated by the burst environment. We compute the evolution of the…