Gamma-ray bursters as sources of cosmic rays

The recent detection of delayed, low energy emission from Gamma-Ray Burst (GRB) sources confirmed the cosmological origin of the bursts and provided support for models where GRBs are produced by the dissipation of the kinetic energy of relativistic fireballs. In this review, ultra high energy, >10^{19} eV, cosmic-ray and high energy, 100 TeV, neutrino production in GRBs is discussed in the light of recent GRB and cosmic-ray observations. Emphasis is put on model predictions t...

The successful discovery of X-ray, optical and radio afterglows of GRB has made possible the identification of host galaxies at cosmological distances. The energy release inferred in these outbursts place them among the most energetic and violent events in the Universe. They are thought to be the outcome of a cataclysmic stellar collapse or compact stellar merger, leading to a relativistically expanding fireball, in which particles are accelerated at shocks and produce nonthe...

Gamma-Ray Bursts (GRBs) have remained a puzzle for many high-energy astrophysicists since their discovery in 1967. With the advent of the X-ray satellites BeppoSAX and RossiXTE, it has been possible to carry out deep multi-wavelength observations of the counterparts associated with the GRBs just within a few hours of occurence, thanks to the observation of the fading X-ray emission that follows the more energetic gamma-ray photons once the GRB event has ended. The fact that t...

We discuss the possibility that the sources for gamma ray bursts are hot neutron stars at cosmological distance scales. The temperature of such stars would be $T \sim 1 \MeV$. Such hot stars can produce an electromagnetic blast wave provided that the ratio of baryon and photon numbers $N_{B}/N_{\gamma} \le 10^{-6}$. The typical time scale for such blasts, the total luminosity, and correlation of gamma ray energy with time of arrival are shown to be roughly consistent with o...

We propose that repeated photoexcitation/ionization of high Z atoms of highly relativistic flows by star light in dense stellar regions followed by emission of decay/recombination photons, which are beamed and boosted to gamma ray energies in the observer frame, produce gamma ray bursts (GRBs). We show that this overlooked mechanism, which is able to convert efficiently baryonic kinetic energy release in merger or accretion induced collapse of neutron stars into cosmological ...

Statistical arguments show that the volume- and time-averaged kinetic power of GRBs and fireball transients (FTs) into an L* galaxy like the Milky Way is at the level of 10^40 ergs/s. This number, though with wide uncertainties related to the internal or external shock efficiency, is sufficient to power hadronic cosmic rays observed locally. The release of energy by the high-mass progenitor stars of GRBs and FTs is sufficient to power the ultrahigh energy cosmic rays, as alre...

I consider the possibility that Ultra High Energy Cosmic Rays are accelerated in Gamma Ray Bursts located in the Galactic corona, thus circumventing the problem raised by Greisen--Zatsepin--Kuz'min cutoff. The acceleration of UHECRs could occur in the pulsars which, in the coronal GRB model, produce them: the same parameters that permit fitting GRBs' observations in the model of Podsiadlowski, Rees and Ruderman (1995) lead to an estimate of the highest achievable energies cor...

The gamma ray burst phenomenon is reviewed from a theoretical point of view, with emphasis on the fireball shock scenario of the prompt emission and the longer wavelenght afterglow. Recent progress and issues are discussed, including spectral-temporal evolution, localizations, jets, spectral lines, environmental and cosmological aspects, as well as some prospects for future experiments in both electromagnetic and non-electromagnetic channels.

Gamma-ray bursts have the potential to produce the particle energies (up to $10^{21}$ eV) and the energy budget ($10^{44} \rm{erg yr^{-1} Mpc^{-3}}$) to accommodate the spectrum of the highest energy cosmic rays; on the other hand, there is no observational evidence yet that they accelerate hadrons. Fermi recently observed two bursts that exhibit a power-law high-energy extension of the typical (Band) spectrum that extends to $\sim 30$ GeV. On the basis of fireball phenomenol...

Active galaxies and gamma ray bursts are the sources of the highest energy photons detected by astronomical telescopes. We speculate that they may be the sources of the highest energy cosmic rays. This makes them true proton accelerators, where the highest energy photons are the decay products of neutral pions photoproduced when the proton beams interacts with ambient radiation. Neutrinos from the decay of charged pions represent an incontrovertible signature for proton accel...