Related papers: Naked-eye optical flash from GRB 080319B: Tracing …
Recent observations suggest that $\gamma$-ray bursts (GRBs) and their afterglows are produced by jets of highly relativistic cannonballs (CBs), emitted in supernova (SN) explosions. The CBs, reheated by their collision with the shell, emit…
The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes -- the activity of the central engine gives rise to the high-energy emission of the burst through internal shocking and…
It is proposed that the baryons in gamma ray burst (GRB) fireballs originate as "pick-up" neutrons that leak in sideways from surrounding baryonic matter and convert to protons in a collision avalanche. The asymptotic Lorentz factor is…
Over the last decade, long-duration gamma-ray bursts (GRBs) including the subclass of X-ray flashes (XRFs) have been revealed to be a rare variety of Type Ibc supernova (SN). While all these events result from the death of massive stars,…
We propose that repeated photoexcitation/ionization of high Z atoms of highly relativistic flows by star light in dense stellar regions followed by emission of decay/recombination photons, which are beamed and boosted to gamma ray energies…
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…
In these proceedings, I discuss recent progress in understanding the nature of cosmic gamma-ray bursts (GRB), with the focus on the apparent relation of several GRBs with an energetic subclass of stellar explosions, type Ib/c core-collapse…
Gamma-ray bursts (GRBs) are the most electromagnetically luminous cosmic explosions. They are powered by collimated streams of plasma (jets) ejected by a newborn stellar-mass black hole or neutron star at relativistic velocities (near the…
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…
With the successful launch of the Swift Gamma-Ray Burst Explorer, people expected the prompt optical flash like GRB990123 would be easily detected. However the fact that early optical flash have not been detected for a number of GRBs…
Very early observations with the Swift satellite of gamma-ray burst (GRB) afterglows reveal that the optical component is not detected in a large number of cases. This is in contrast to the bright optical flashes previously discovered in…
A list of questions regarding Gamma Ray Bursts (GRBs) and Soft Gamma Repeaters (SGRs) remain unanswered within the Fireball-cone and Magnetar explosive scenarios. A persistent, thin (less than micron-sr solid angle) precessing and spinning…
In the neutron-rich internal shocks model for Gamma-ray Burts (GRBs), the Lorentz factors (LFs) of ions shells are variable, so are the LFs of accompanying neutron shells. For slow neutron shells with a typical LF tens, the typical…
Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed $\gamma$ rays along the…
Gamma-ray bursts (GRBs) are the most brilliant objects in the Universe but efforts to estimate the total energy released in the explosion -- a crucial physical quantity -- have been stymied by their unknown geometry: spheres or cones. We…
The observations of gamma-ray bursts (GRBs) such as 980425, 031203 and 060218, with luminosities much lower than those of other classic bursts, lead to the definition of a new class of GRBs -- low-luminosity GRBs. The nature of the outflow…
Very early optical and near infrared (IR) emission was discovered accompanying the long gamma-ray burst (GRB) 041219a. We show that the optical/IR flash tracking the gamma-ray lightcurve during the prompt emission could be understood as…
In the neutron-rich internal shocks model for gamma-ray bursts (GRBs), the Lorentz factors (LFs) of ion shells are variable, and so are the LFs of accompanying neutron shells. For slow neutron shells with a typical LF of approximate tens,…
Gamma-Ray Bursts (GRBs) are expected to efficiently accelerate protons up to relativistic energies. High-energy photons can originate from decay of neutral pions produced by the interaction of these protons with the medium surrounding the…
Highly variable gamma-ray pulses and X-ray flares in GRB light curves can result from external shocks rather than central engine activity under the assumption that the GRB blast-wave shell does not spread. Acceleration of cosmic rays to…