Related papers: Composition of cosmic rays accelerated in active g…
We explore scenarios where the highest energy cosmic rays (HECR) are produced by new particle physics near the grand unification scale. Using detailed numerical simulations of extragalactic cosmic and gamma-ray propagation, we show the…
We investigate the dependence of composition, spectrum and angular distributions of ultra-high energy cosmic rays above 10^19 eV from individual sources on their magnetization. We find that, especially for sources within a few megaparsecs…
Cosmic rays (CRs) play a decisive role within our own Galaxy. They provide partial pressure support against gravity, they trace past energetic events such as supernovae, and they reveal the underlying structure of the baryonic matter…
Transrelativistic supernovae (SNe), which are likely driven by central engines via jets or winds, have been among candidate sources of ultrahigh-energy cosmic rays (UHECRs). We investigate acceleration and survival of UHECR nuclei in the…
We investigate the shock acceleration of particles in massive galaxy mergers or collisions, and show that cosmic rays (CRs) can be accelerated up to the second knee energy ~0.1-1 EeV and possibly beyond, with a hard spectral index Gamma ~…
Recent observations by CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic ray (CR) helium is harder than that of CR proton below the knee 10^15 eV and (2) all CR spectra become hard at > 10^11 eV/n. We propose a new…
The origin of the bulk of cosmic rays (CRs) observed at Earth is the topic of a century long investigation, paved with successes and failures. From the energetic point of view, supernova remnants (SNRs) remain the most plausible sources of…
One of the most essential but uncertain processes for producing cosmic-rays (CRs) and their spectra is how accelerated particles escape into the interstellar space. We propose that the CR electron spectra at >~TeV energy can provide a…
Cosmic rays are the highest energy particles found in nature. Measurements of the mass composition of cosmic rays between 10^{17} eV and 10^{18} eV are essential to understand whether this energy range is dominated by Galactic or…
Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the "knee" of the CR spectrum at 10^15 eV, accelerating particles to relativistic energies in their blast waves by the process of diffusive shock…
Recent observations found that electrons are accelerated to $\sim$10 GeV and emit synchrotron hard X-rays in two magnetic white dwarfs (WDs), also known as cataclysmic variables (CVs). In nova outbursts of WDs, multi-GeV gamma-rays were…
We have developed a model that explains cosmic rays with energies E between \~0.3 PeV and the energy of the second knee at E_2 ~ 3*10^{17} eV as originating from a recent Galactic gamma-ray burst (GRB) that occurred ~1 Myr ago within 1 kpc…
The present paper deals with calculations based on a standard model of cosmic ray acceleration in Supernova remnants (SNR) and on the latest astronomical data concerning the variety in Supernovae types, energies as well as the sites of…
It is shown that the acceleration of particles by a powerful relativistic jet associated with the activity of a supermassive black hole in the Galactic center several million years ago may explain the observed cosmic ray spectrum at…
The characteristics relating to the lateral and longitudinal development of EAS in the energy region of 10^15-10^19eV have been analyzed in the framework of the QGSJET model and of mass composition of primary cosmic rays. It is found that…
We consider the possibility that the excess of cosmic rays near $\sim 10^{18}$ eV, reported by the AGASA and SUGAR groups from the direction of the Galactic Center, is caused by a young, very fast pulsar in the high density medium. The…
Recent measurements of the positron/electron ratio in the cosmic ray (CR) flux exhibits an apparent anomaly, whereby this ratio increases between 10 and 100 GeV. In contrast, this ratio should decrease according to the standard scenario, in…
The differential energy spectrum of cosmic rays from Cherenkov radiation measurements in EAS in the energy range of 10^15-10^20eV has been compared with an anomalous diffusion model for the particles in interstellar space having fractal…
The recent observations revealed that the cosmic-ray (CR) proton spectrum showed a complex structure: the hardening at $\rm \sim 200~GeV$ and softening at $\rm \sim 10~TeV$. However, so far the physical origins of this spectral feature…
We propose that ultra-high-energy (UHE) cosmic rays (CRs) above $10^{18}$eV are produced in relativistic jets of powerful active galactic nuclei via an original mechanism, which we dub "espresso" acceleration: "seed" galactic CRs with…