Related papers: Probing Cosmic Accelerators Using VHE Gamma Rays a…
The search for gamma radiation in clusters of galaxies represents a precious tool to investigate the history of these large scale structures. Clusters or sources within them accelerate cosmic rays, as demonstrated by the detection of radio…
The IceCube Neutrino Observatory has recently found compelling evidence for a particular blazar producing high-energy neutrinos and $\mathrm{PeV}$ cosmic rays, however the sources of cosmic rays above several $\mathrm{EeV}$ remain…
If supernova remnants (SNRs) are the sites of cosmic-ray acceleration, the associated nuclear interactions should result in observable fluxes of TeV gamma-rays from the nearest SNRs. Measurements of the gamma-ray flux from six nearby,…
Gamma-ray bursts (GRBs) are one of the candidates of ultra-high-energy (around 10^18.5 eV) cosmic-ray (UHECR) sources. We investigate high-energy cosmic-ray acceleration including heavy nuclei in GRBs by using Geant 4, and discuss its…
We discuss the relation between the acceleration spectra of extragalactic cosmic ray protons and the luminosity and cosmological evolution of their sources and the production of ultra high energy cosmogenic neutrinos in their propagation…
Ultra-high energy cosmic rays (UHECRs) accelerated in the jets of active galactic nuclei can accumulate in high magnetic field, ~100 kpc-scale regions surrounding powerful radio galaxies. Photohadronic processes involving UHECRs and photons…
The suggested association between the sources of gamma-ray bursts (GRB's) and the sources of ultra-high energy cosmic rays (UHECR's) is based on two arguments: (i) The average energy generation rate of UHECR's is similar to the gamma-ray…
Clusters of galaxies and the large scale filaments that connect neighboring clusters are expected to be sites of acceleration of charged particles and sources of non-thermal radiation from radio frequencies to gamma rays. Gamma rays are…
We present a novel method for the search of high energy extraterrestrial neutrinos in extended regions. The method is based on the study of the spatial correlations between the events recorded by neutrino telescopes. Extended regions…
Cosmic ray nuclei, cosmic ray electrons with energy above a few GeV, and the diffuse gamma-ray background radiation (GBR) above a few MeV, presumed to be extragalactic, could all have their origin or residence in our galaxy and its halo.…
The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely associated with the most energetic processes…
We discuss the production of ultra high energy neutrinos coming from the propagation of ultra high energy cosmic rays and in the framework of top-down models for the production of these extremely energetic particles. We show the importance…
Gamma-ray bursts (GRBs) have long been held as one of the most promising sources of ultra-high energy (UHE) neutrinos. The internal shock model of GRB emission posits the joint production of UHE cosmic ray (UHECRs, above 10^8 GeV), photons,…
The origin of ultra-high-energy cosmic rays (UHECRs) remains an open questions in astrophysics. We explore two primary scenarios for the distribution of UHECR sources, assuming that their production rate follows either the cosmic…
Interactions of ultra-high-energy cosmic rays with background photons set a limit to the distance cosmic rays reaching us above a certain energy can originate from, making measurements of their fluxes insensitive to properties of sources at…
The current status of the ultrahigh energy cosmic ray (UHE CR) enigma and several proposed solutions involving particle physics beyond the standard model are discussed. Emphasis is given to top--down models, and as a main example,…
Galactic PeVatrons are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact hadronically with nearby ambient gas or the interstellar medium, resulting in…
We briefly discuss three aspects related to the origin of ultra-high energy cosmic rays (UHECRs) namely: 1) particle acceleration in astrophysical sources; 2) transition to an extragalactic origin; 3) spectrum and anisotropies at the…
We investigate the idea that ultrahigh energy gamma-rays (E>10 TeV) can be produced when charged particles are accelerated by microscopic black holes. We begin by showing that microscopic black holes may exist as remnants of primordial…
It is generally believed that pulsars dissipate their rotational energy through powerful winds of relativistic particles. Confinement of these winds leads to the formation of luminous pulsar wind nebulae (PWNe) seen across the…