Related papers: Very High Lorentz Factor Fireballs and Gamma-Ray B…
It has been established that Gamma-Ray Bursts (GRB) can produce Very High Energy radiation (E > 100 GeV), opening a new window on the investigation of particle acceleration and radiation properties in the most energetic domain. We expect…
We propose a new mechanism for the prompt emission of gamma-ray burst. In our model electrons are continuously accelerated in the post shock region via plasma turbulence. Using the Monte Carlo technique, we mimic the second-order Fermi…
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…
GRB 220627A, detected by Fermi Gamma-ray Burst Monitor (GBM), shows two episodes of gamma-ray emission, which are separated by a {$\sim$700} s long quiescent phase. Due to similar temporal shapes and spectra in the two episodes, GRB 220627A…
Despite more than fifty years of gamma-ray burst (GRB) observations, several questions regarding the origin of the prompt emission, particularly at high energies, remain unresolved. We present a comprehensive analysis of 35 GRBs observed by…
The recently discovered TeV emission from Gamma-Ray Bursts (GRBs) hints towards a possible hadronic origin of this radiation component. We developed a Monte Carlo (MC) simulation reproducing the kinematics of photo-hadronic interactions at…
We analyze the MeV/GeV emission from four bright Gamma-Ray Bursts (GRBs) observed by the Fermi-Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum…
We calculate and discuss the light element freeze-out nucleosynthesis in high entropy winds and fireballs for broad ranges of entropy-per-baryon, dynamic timescales characterizing relativistic expansion, and neutron-to-proton ratios. With…
It is generally accepted that gamma-ray bursts (GRBs) are initiated by a relativistic pair fireball, converting its internal energy into kinetic energy of a relativistically moving plasmoid and subsequently into radiation. Here, we…
We present the first general relativistic hydrodynamic models of the launch and evolution of relativistic jets and winds, driven by thermal energy deposition, possibly due to neutrino-antineutrino annihilation, in the close vicinity of…
GRB 190114C is the first gamma-ray burst detected at Very High Energies (VHE, i.e. >300 GeV) by the MAGIC Cherenkov telescope. The analysis of the emission detected by the Fermi satellite at lower energies, in the 10 keV -- 100 GeV energy…
The collapse of massive stars drives explosions that power relativistic fireballs. If only a small amount of matter is entrained, such clean fireballs can expand with Lorentz factors $\Gamma> 100$, accounting for gamma-ray bursts (GRBs). It…
Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe and are powered by ultra-relativistic jets. Their prompt $\gamma$-ray emission briefly outshines the rest of the $\gamma$-ray sky making them detectable from…
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…
The interaction of a relativistic fireball with its ambient medium is described through two shocks: a reverse shock that propagates into the fireball, and a forward shock that propagates into the medium. The observed optical flash of GRB…
The high energy GeV emission of gamma-ray bursts (GRBs), detected by \emph{Fermi}/LAT, has a significantly different morphology compared to the lower energy MeV emission, detected by \emph{Fermi}/GBM. Though the late time GeV emission is…
Recent studies of photon-generation mechanisms in the color-superconducting Color-Flavor Locked (CFL) phase of dense quark matter have found gamma-ray emissivities in excess of ~ 10^{50} erg cm^{-3} s^{-1} for temperatures in the 10-30 MeV…
Sub-photospheric internal shocks and transverse differences of the bulk Lorentz factor in relativistic fireball models of GRB lead to neutron diffusion relative to protons, resulting in inelastic nuclear collisions. This produces…
The Lorentz violation~(LV) effect of ultra-relativistic particles can be tested by gamma-ray burst~(GRB) neutrinos and photons. The IceCube Collaboration has observed plenty of ultra-high energy neutrinos, including four events of PeV scale…
The prompt emission of gamma-ray bursts (GRBs) is widely thought to be radiation from accelerated electrons, but an appreciably larger amount of energy could be carried by accelerated protons, particularly if GRBs are the sources of…