We calculate the high energy (sub-GeV to TeV) prompt and afterglow emission of GRB 080319B that was distinguished by a naked-eye optical flash and by an unusual strong early X-ray afterglow. There are three possible sources for high energy emission: the prompt optical and γ-ray photons IC scattered by the accelerated electrons, the prompt photons IC scattered by the early external reverse-forwa...

The content of extremely high energy (EHE) photons in the highest energy cosmic rays can be investigated by analyzing showers arriving from directions where the perpendicular component of the Earth's magnetic field is high or showers arriving from the region surrounding the Sun. We perform Monte Carlo simulations of cascades initiated by photons with parameters of the highest energy showers obs...

Eleven bright gamma-ray bursts (GRBs) detected by BATSE have also been seen at much higher energies by EGRET, six at energies above 10 MeV. Most distinctive among these is GRB940217, which includes long duration, hard gamma-ray emission and the most energetic GRB photon detection to date, around 18 GeV. Such observations imply that these bursts are optically thin to photon-photon pair productio...

Within the internal shock scenario we consider different mechanisms of high energy photon production inside a Gamma Ray Burst (GRB) fireball and derive the expected high energy photon spectra from individual GRBs during the prompt phase. The photon spectra of leptonic and hadronic origins are compared within different sets of parameter regimes. Our results suggest that the high energy emission ...

Recent observations show that hypernovae may deposit some fraction of their kinetic energy in mildly relativistic ejecta. In the dissipation process of such ejecta in a stellar wind, cosmic ray protons can be accelerated up to ∼ 10 eV. We discuss the TeV to MeV gamma-ray and the X-ray photon signatures of cosmic rays accelerated in hypernovae. Secondary X-ray photons, emitted by electron-positr...

We calculate the high energy (sub-GeV to TeV) prompt and afterglow emission of GRB 080319B that was distinguished by a naked-eye optical flash and by an unusual strong early X-ray afterglow. There are three possible sources for high energy emission: the prompt optical and γ-ray photons IC scattered by the internal shock electrons, the prompt photons IC scattered by the early external reverse-fo...

This experiment gives you the opportunity to study high energy photons from radioactive decays. These photons have energies that are characteristic of the specific initialand finalstate nuclear energy levels and therefore provide a means of studying the energy levels (similar to the use of optical photons to study electronic energy levels in atoms), nuclear reactions, and also provide a way to ...

We report a calculation of the expected rate of inclined air showers induced by ultra high energy cosmic rays to be obtained by the Auger Southern Observatory assuming different mass compositions. We describe some features that can be used to distinguish photons at energies as high as 10 20 eV. The discrimination of photons at such energies will help to test some models of the origin of ultra-h...

Given the present knowledge about strong interaction, one has to assume that in collisions of heavy nuclei with sufficiently high kinetic energy, a high-energy-density region can be formed in which the hadrons dissolve into their constituents, i.e., into quark-gluon Several estimates2 lead to 0.5-2 ~ e ~ / f m ~ or the critical energy density. The quark-gluon plasma represents a new physical ph...