Related papers: A cosmic Zevatron based on cyclotron auto-resonanc…
The term PeVatron designates astrophysical objects capable of accelerating particles to PeV energies. Their nature and particle acceleration mechanisms are uncertain, but ultra-high-energy gamma rays are produced when particles accelerated…
Ultrarelativistic particles called cosmic rays permeate the Milky Way, propagating through the Galactic turbulent magnetic fields. The mechanisms under which these particles increase their energy can be reasonably described by current…
Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultra high energies. Here we present simulation results…
The Cygnus Cocoon is the first gamma-ray superbubble powered by a massive stellar association, the OB2 association. It was postulated that the combined effects of the stellar winds of all the massive O-type stars of the OB2 association can…
Centaurus A, the closest active galaxy, has been detected from radio to high-energy gamma-rays. The synchrotron radiation by extremely high energy protons may be a suitable mechanism to explain the MeV to GeV emission detected by the…
We study the acceleration of ultra-high-energy cosmic rays (UHECRs) at FR-II radio galaxies by performing Monte Carlo simulations for the transport, scattering, and energy change of the CR particles injected into the time-evolving jet flows…
We shortly discuss several astrophysical scenarios leading to cosmic ray acceleration up to extremely high energies reaching the scale of 10^{20} eV. The processes suggested in the literature include acceleration at relativistic jet…
It is widely believed that Galactic Cosmic Rays (CR) are accelerated in Supernova Remnants (SNRs) through the process of diffusive shock acceleration. In this scenario, particles should be accelerated up to energies around 1 PeV (the…
The detection of the Amaterasu event of energy 244 EeV by the Telescope Array, one of the most energetic ultrahigh-energy cosmic rays (UHECRs; $E\gtrsim0.1$ EeV) observed to date, invites scrutiny of its potential source. We investigate…
Recent observations of cosmic rays increasingly point to the existence of nearby sources - so-called "local tevatrons", capable of accelerating particles to TeV energies. In this study, we examine the potential of a typical main-sequence…
The photomeson production in ultra-high-energy cosmic-ray (UHECR) accelerators such as gamma-ray bursts and active galaxies may lead to ultra-high-energy (UHE) gamma-ray emission. We show that generation of UHE pairs in magnetized…
Ultra high energy cosmic rays (UHECRs), with energies above ~6 x 10^19 eV, seem to show a weak correlation with the distribution of matter relatively near to us in the universe. It has earlier been proposed that UHECRs could be accelerated…
Ultra High Cosmic Rays (UHECR) Astronomy may be correlated to a primary parental Neutrino Astronomy: indeed any far BL Lac Jet or GRB, sources of UHECR, located at cosmic edges, may send its signal, overcoming the severe GZK cut-off, by…
The search for Galactic pevatrons is now a well-identified key science project of all instruments operating in the very-high-energy domain. Indeed, in this energy range, the detection of gamma rays clearly indicates that efficient particle…
The process of diffusive acceleration of charged particles in shocked plasmas is widely invoked in astrophysics to account for the ubiquitous presence of signatures of non-thermal relativistic electrons and ions in the universe. A key…
We find the general requirements, set by classical electrodynamics, to the sources of extremely high-energy cosmic rays (EHECRs). It is shown that the parameters of EHECR accelerators are strongly limited not only by the particle…
We introduce neutrino astronomy starting from the observational fact that Nature accelerates protons and photons to energies in excess of 10^{20} and 10^{13} eV, respectively. Although the discovery of cosmic rays dates back a century, we…
We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in…
We propose that a hierarchical shock model$\unicode{x2014}$including supernova remnant shocks, galactic wind termination shocks, and accretion shocks around cosmic filaments and galaxy clusters$\unicode{x2014}$can naturally explain the…
The Earth is bombarded by ultra-relativistic particles, known as cosmic rays (CRs). CRs with energies up to a few PeV (=10$^{15}$ eV), the knee in the particle spectrum, are believed to have a Galactic origin. One or more factories of PeV…