Related papers: Constraints on the Synchrotron Emission Mechanism …
The detection of a very-high-energy TeV spectral component in the afterglow emission of gamma-ray bursts (GRBs) has opened a new probe into the energetics of ultra-relativistic blast waves and the nature of the circumburst environment in…
The mechanism that causes the prompt-emission episode of gamma-ray bursts (GRBs) is still widely debated despite there being thousands of prompt detections. The favoured internal shock model relates this emission to synchrotron radiation.…
We describe our attempt to determine if gamma-ray burst (GRB) and afterglow emissions could both arise in external shocks for simple GRBs--bursts consisting of just a few peaks in their lightcurves. We calculate peak flux and peak frequency…
Observations of gamma-ray burst (GRB) afterglows have long provided the most detailed information about the origin of this spectacular phenomena. The model that is most commonly used to extract physical properties of the event from the…
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…
After almost 4 years of operation, the two instruments onboard the Fermi Gamma-ray Space Telescope have shown that the number of gamma-ray bursts with high energy photon emission above 100 MeV cannot exceed roughly 9% of the total number of…
We explore a one-zone hadronic model that may be able to reproduce $\gamma$-ray burst (GRB) prompt emission with a minimum of free parameters. Assuming only that GRBs are efficient high-energy proton accelerators and without the presence of…
A large fraction of gamma-ray burst (GRB) spectra are very hard below the peak. Indeed, the observed distribution of sub-peak power-law indices, $\alpha$, has been used as an argument for a photospheric origin of GRB spectra. Here, we…
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…
The proton synchrotron radiation is considered as the origin of high-energy emission of blazars at times. However, extreme physical parameters are often required. In this work, we propose an analytical method to study the parameter space…
The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues…
Studies of gamma-ray bursts (GRBs) and their multi-wavelength afterglows have led to insights in electron acceleration and emission properties from relativistic, high-energy astrophysical sources. Broadband modeling across the…
Fermi observations of GeV emission from GRBs have suggested that the Lorentz factor of some GRBs is around a thousand or even higher. At the same time the same Fermi observations have shown an extended GeV emission indicating that this…
Synchrotron radiation from a decelerating blastwave is a widely accepted model of radio to X-ray afterglow emission from gamma-ray bursts (GRBs). GeV gamma-ray emission detected by the Fermi Large Area Telescope (LAT) and the duration of…
It is shown that when an few-cycle, relativistically intense, p-polarized laser pulse is obliquely incident on overdense plasma, the surface electrons may form ultra-thin, highly compressed layers, with a width of a few nanometers. These…
von Kienlin et al. (2019) selected 11 short gamma-ray bursts (sGRBs) whose characteristics are similar to GRB 170817A. These bursts, like GRB 170817A, have a hard spike followed by a soft thermal tail. However, as their redshifts are…
In the internal shock model for gamma-ray bursts (GRBs), the synchrotron spectrum from the fast cooling electrons in a homogeneous downstream magnetic field (MF) is too soft to produce the low-energy slope of GRB spectra. However the…
The detection in 10 bursts of an optical counterpart emission (i.e. during the prompt GRB phase) that is 10-10000 brighter than the extrapolation of the burst spectrum to optical frequencies suggests a synchrotron self-Compton origin for…
We propose a direct and model-independent method to constrain the Lorentz factor of a relativistically expanding object, like gamma-ray bursts. Only the measurements, such as thermal component of the emission, the distance and the variable…
The properties of gamma-ray bursts (GRBs) that are inferred from observations depend on the value of the bulk Lorentz factor, $\Gamma$. Consequently, accurately estimating it is an important aim. In this work, we present a method of…