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Roughly half of the observed gamma-ray bursts (GRBs) may arise from the shocking of an ultra-relativistic shell of protons with the interstellar medium (ISM). Any neutrons originally present in the GRB fireball may, depending on the…
Observations imply that gamma-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a highly relativistic fireball. Photo-meson interactions of protons with gamma-rays within the fireball dissipation region are expected…
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…
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…
We investigate, independently of specific emission models, the constraints on the value of the bulk Lorentz factor Gamma of a fireball. We assume that the burst emission comes from internal shocks in a region transparent to Thomson…
Neutrons play an important role in the dynamics of gamma-ray bursts. The presence of neutrons in the baryon-loaded fireball is expected. If the neutrons abundance is comparable to that of protons, important features may be observed such as…
Knowledge of the bulk Lorentz factor $\Gamma_{0}$ of GRBs allows us to compute their comoving frame properties shedding light on their physics. Upon collisions with the circumburst matter, the fireball of a GRB starts to decelerate,…
Long-duration gamma-ray bursts (LGRBs), thought to be produced during core-collapse supernovae, may have a prominent neutron component in the outflow material. If present, neutrons can change how photons scatter in the outflow by reducing…
The fireball, the promising model of the gamma-ray burst (GRB), is an opaque radiation plasma, whose energy is significantly greater than its rest mass. We numerically simulate the evolution of the fireball heated by the…
We study three processes that shape the nuclear composition of GRB fireballs: (1) neutronization in the central engine, (2) nucleosynthesis in the fireball as it expands and cools, and (3) spallation of nuclei in subsequent internal shocks.…
Observations imply that gamma-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a highly relativistic fireball. Photo-meson interactions of protons with gamma-rays within the fireball dissipation region are expected…
We point out that the baryon-loading problem in Gamma-Ray Burst (GRB) models can be amelioriated if a significant fraction of the baryons which inertially confine the fireball are converted to neutrons. A high neutron fraction in some…
We study the properties of a significant thermal emission component that was identified in 47 GRBs observed by different instruments. Within the framework of the "fireball" model, we deduce the values of the Lorentz factor Gamma, and the…
We consider gamma-ray burst outflows with a substantial neutron component that are either dominated by thermal energy (fireballs) or by magnetic energy. In the latter case, we focus on the recently introduced `AC' model which relies on…
Following Waxman and Bahcall we calculate the event rate, energy and zenith angle dependence of neutrinos produced in the fireball model of gamma ray bursts (GRB). We emphasize the primary importance of i) burst-to-burst fluctuations and…
Gamma ray bursts (GRBs) are thought to originate from highly relativistic jets. The fireball model predicts internal shocks in the jets, causing magnetic field to be amplified and particles to be accelerated. We model the effects of an…
The neutrino self-energy is calculated in a weakly magnetized plasma consists of electrons, protons, neutrons and their anti-particles and using this we have calculated the neutrino effective potential up to order $M^{-4}_W$. In the absence…
Fireballs of gamma-ray bursts are partially made of free neutrons. Their presence crucially changes the mechanism of the fireball deceleration by an external medium. At late stages of the explosion, neutrons fully decouple from ions and…
Relativistic neutron-loaded outflows in gamma-ray bursts are studied at their early stages, before deceleration by a surrounding medium. The outflow has four components: radiation, electrons, protons and neutrons. The components interact…
The energy release in gamma-ray bursts is one of the most interesting clues on the nature of their "inner engines". We show here that the total energy release in GRBs varies by less than one order of magnitude from one burst to another…