We present new observations of the isotopic composition of low-energy He, C, N, 0, and Ne nuclei. The observations cover the energy interval from ,...., 5 to 30 MeV per nucleon, the energy range where the "anomalous cosmic ray" fluxes of He, N, 0, and Ne have been observed. We compare the isotopic composition of the anomalous cosmic rays with that of higher-energy galactic cosmic rays in an eff...

Recent evidence for a large Galactic halo, based on cosmic-ray radioactive nuclei, implies a significant contribution from inverse Compton emission at high Galactic latitudes. We present predictions for the expected intensity distribution, and show that the EGRET gamma-ray latitude distribution is well reproduced from the plane to the poles. We show that the Galactic component at high latitudes...

We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, γ-rays, and synchrotron radiation. Our main results include evaluation of diffusion/convection and reacceleration models, estimates of the halo size, calculations of the interstellar positron and ant...

We consider a jet-disk symbiosis model to explain Gamma Ray Bursts and their afterglows. It is proposed that GRBs are created inside a pre-existing jet from a neutron star in a binary system which collapses to a black hole due to accretion. In our model we assume that a fraction of the initial energy due to this transition is deposited in the jet by magnetic fields. The observed emission is the...

The maximum cosmic ray energy achievable by acceleration by a relativistic blast wave is derived. It is shown that forward shocks from long GRB in the interstellar medium are powerful enough to produce the Galactic cosmic-ray component just below the ankle at 4 × 10eV, as per an earlier suggestion (Levinson & Eichler 1993). It is further argued that, were extragalactic long GRBs responsible for...

Big bang nucleosynthesis (BBN) and the cosmic baryon density from cosmic microwave background anisotropies together predict a primordial Li abundance a factor of 2–3 higher than that observed in galactic halo dwarf stars. A recent analysis of Li observations in halo stars, using significantly higher surface temperature for these stars, found a higher Li plateau abundance. These results go a lon...

Diffuse Galactic gamma-ray emission is produced in interactions of cosmic rays with gas and ambient photon fields and thus provides us with an indirect measurement of cosmic rays in various locations in the Galaxy. The diffuse gamma-ray continuum is more intense than expected both at energies below 200 keV and above 1 GeV. The existing models for the high-energy excess are reviewed in the light...

The γ-ray sky as we know it today is a composite of the emission from point sources and diffuse emission (see Fig.1). The most prominent feature is the galactic plane, in which interactions between cosmic rays and the thermal gas lead to γ-ray emission by π-decay and bremsstrahlung. On top of this diffuse emission we see point sources all over the map, part of them being pulsars, another part d...

We consider a jet-disk symbiosis model to explain Gamma Ray Bursts and their afterglows. It is proposed that GRBs are created inside a pre-existing jet from a neutron star in a binary system which collapses to a black hole due to accretion. In our model we assume that a fraction of the initial energy due to this transition is deposited in the jet by magnetic elds. The observed emission is then ...