Related papers: UHECRs from the Radio Lobes of AGNs
The origin of the highest energy cosmic rays remains an enigma. They offer a window to new physics, including tests of physical laws relevant to their propagation and interactions, at energies unattainable by terrestrial accelerators. They…
New particle acceleration schemes open up exciting opportunities, potentially providing more compact or higher-energy accelerators. The AWAKE experiment at CERN is currently taking data to establish the method of proton-driven plasma…
In the past decade, a new class of bright transient radio sources with millisecond duration has been discovered. The origin of these so-called Fast Radio Bursts (FRBs) is still a great mystery despite the growing observational efforts made…
We have published the energy spectrum of ultra-high energy cosmic rays (UHECRs) for E > 10^18.2 eV from our first 5-year observation with the surface detectors of Telescope Array. We found two breaking points in the power-law spectrum, a…
Studies of gamma-ray bursts (GRBs) and their multi-wavelength afterglows have led to insights in electron acceleration and emission properties from relativistic, high-energy astrophysical sources. Broadband modeling across the…
We discuss, in terms of particle acceleration, the results from optical VLT observations of hot spots associated with radio galaxies. On the basis of observational and theoretical grounds, it is shown that: 1. relatively low radio-radio…
Fast radio bursts (FRBs) are sufficiently energetic to be detectable from luminosity distances up to at least seven billion parsecs (redshift $z > 1$). Probing the maximum energies and luminosities of FRBs constrains their emission…
A Tevatron is an accelerator capable of imparting TeV energies to particles like a proton (1 TeV = $10^{12}$ eV). By analogy, a Zevatron is an accelerator scheme envisaged to accelerate particles to ZeV energies (1 ZeV = $10^{21}$ eV).…
A novel model of particle acceleration in the rotating magnetospheres of active galactic nuclei (AGN) and pulsars is constructed. The particle energies may be boosted up to enormous energies in a several step mechanism. In the first stage,…
The dependence E_h (N_e) of Extensive Air Shower (EAS) hadronic component energy flux on the number N_e of particles in EAS is investigated in the primary energy range of the order of 10^{15} - 10^{17} eV. The work was aimed at checking the…
The detection of astrophysical very high energy (VHE) neutrinos in the range of TeV-PeV energies by the IceCube observatory has opened a new season in high energy astrophysics. Energies ~PeV imply that the neutrinos are originated from…
Particle cascades initiated by ultra-high energy (UHE) neutrinos in the lunar regolith will emit an electromagnetic pulse with a time duration of the order of nano seconds through a process known as the Askaryan effect. It has been shown…
Hadronic supercriticalities are radiative instabilities that appear when large amounts of energy are stored in relativistic protons. When the proton energy density exceeds some critical value, a runaway process is initiated resulting in the…
Electrons with kinetic energies of the order 100 keV are capable of exciting atomic vibrational states from a distance of microns. Despite such a large interaction distance, our detailed calculations show that the scattering physics permits…
Recent precise measurements of cosmic ray (CR) spectra show that the energy distribution of protons is softer than those of heavier nuclei, and there are spectral hardenings for all nuclear compositions above $\sim$200 GV. Models proposed…
We argue that an astrophysical solution to UHECR problem is viable. The pectral features of extragalactic protons interacting with CMB are calculated in model-independent way. Using the power-law generation spectrum $\propto E^{-\gamma_g}$…
We derive simple analytic expressions for the flux and spectrum of ultra-high energy cosmic-rays (UHECRs) predicted in models where the CRs are protons produced by extra-Galactic sources. For a power-law scaling of the CR production rate…
We present a model for high-energy emission in microquasars where the energy content of the jets is dominated by relativistic protons. We also include a primary leptonic component. Particles are accelerated up to relativistic energies in a…
We consider the problem of the cosmic ray spectrum formation assuming that cosmic rays are produced by Galactic sources. The anomalous diffusion equation proposed in our recent papers is used to describe cosmic ray propagation in the…
We show that all features of the ultrahigh energy cosmic ray spectrum from 10^{17} eV to 10^{21} eV can be described with a simple power-like injection spectrum of protons under the assumption that the neutrino-nucleon cross-section is…