Related papers: Optical and gamma-ray emissions from internal forw…
This paper introduces a kinetic code that simulates gamma-ray burst (GRB) afterglow emission from the external forward shock and presents examples of some of its applications. One interesting research topic discussed in the paper is the…
While it is generally agreed that the emitting regions in Gamma-Ray Bursts (GRBs) move ultra relativistically towards the observer, different estimates of the initial Lorentz factors, $\Gamma_0$, lead to different, at times conflicting…
A popular paradigm to explain the rapid temporal variability observed in gamma-ray burst (GRB) lightcurves is the internal shock model. We propose an alternative model in which the radiating fluid in the GRB shell is relativistically…
The observational diversity of optical emission, which coincides with prompt gamma-ray bursts (GRBs), has been discovered in the recent Swift era. We show that on the assumption of the synchrotron radiation for the observed energy range…
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,…
Fermi observations of high-energy gamma-ray emission from GRB 080916C shows that its spectrum is consistent with the Band function from MeV to tens of GeV. Assuming one single emission mechanism dominates in the whole energy range, we show…
The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB $\textit{141028A}$, is analyzed under the guise of an external shock model. First, we fit the $\gamma$-ray spectrum with a two-component photon model, namely…
We discuss the GeV to TeV photon emission of gamma-ray bursts (GRBs) within the refreshed shock and the continuous injection scenarios, motivated by the observation of extended emission in a substantial fraction of short GRBs. In the first…
Unsteady activity of gamma-ray burst sources leads to internal shocks in their emergent relativistic wind. We study the emission spectra from such shocks, assuming that they produce a power-law distribution of relativistic electrons and…
A leading mechanism for producing cosmological gamma-ray bursts (GRBs) is via ultra-relativistic particles in an expanding fireball. The kinetic energy of the particles is converted into thermal energy in a forward shock and a reverse…
In the external shock model, gamma-ray burst (GRB) emissions are produced by the energization and deceleration of a thin relativistic blast wave due to its interactions with the circumburst medium (CBM). We study the physical properties of…
A generic synchrotron external shock model is the widely preferred paradigm used to interpret the broad-band afterglow data of gamma-ray bursts (GRBs), including predicted observable signatures from a reverse shock which have been confirmed…
Using GRB 991216 as a prototype, it is shown that the intensity substructures observed in what is generally called the "prompt emission" in gamma ray bursts (GRBs) do originate in the collision between the accelerated baryonic matter (ABM)…
We construct models for gamma-ray bursts where the emission comes from internal shocks in a relativistic wind with a highly non uniform distribution of the Lorentz factor. We follow the evolution of the wind using a very simplified approach…
We assume that internal shocks of Gamma Ray Bursts (GRBs) consist of multiple sub-jets with a collimation half-angle $\sim {\rm several }\times\gamma_i^{-1}$, where $\gamma_i$ is the Lorenz factor of each sub-jet. If by chance a sub-jet is…
It is proposed that the prompt emission observed in bursts that exhibit a thermal component originates from relativistic radiation mediated shocks that form below the photosphere of the GRB outflow. It is argue that such shocks are expected…
We analyze the >100MeV data for 3 GRBs detected by Fermi (GRBs 080916C, 090510, 090902B) and find that these photons were generated via synchrotron emission in the external forward shock. We arrive at this conclusion by four different…
In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with…
Assuming that the early optical emission is dominated by the external reverse shock (RS) in the standard model of gamma-ray bursts (GRBs), we intend to constrain RS models with the initial Lorentz factor $\Gamma_0$ of the outflows based on…
The extremely bright optical flash that accompanied GRB 080319B suggested, at first glance, that the prompt $\gamma$-rays in this burst were produced by Synchrotron self Compton (SSC). We analyze here the observed optical and $\gamma$…