Related papers: Frontiers in High-Energy Astroparticle Physics
Recently, the IceCube collaboration made a big announcement of the first discovery of high-energy cosmic neutrinos. Their origin is a new interesting mystery in astroparticle physics. The present multimessenger data may give us hints of…
We discuss theoretical issues and experimental data that brought the ultra high energy cosmic rays in the list of Nature's greatest puzzles. After many years of research we still do not know how astrophysical acceleration processes can…
Astrophysical neutrinos can be produced in proton interactions of charged cosmic rays with ambient photon or baryonic fields. Cosmic rays are observed in balloon, satellite and air shower experiments every day, from below 1e9 eV up to…
Very high energy {\gamma}-rays are one of the most important messengers of the non-thermal Universe. The major motivation of very high energy {\gamma}-ray astronomy is to find sources of high energy cosmic rays. Several astrophysical…
We apply new upper limits on neutrino fluxes and the diffuse extragalactic component of the GeV gamma-ray flux to various scenarios for ultra high energy cosmic rays and neutrinos. As a result we find that extra-galactic top-down sources…
The observation of twenty cosmic-ray air-showers at and above 10^{20} eV poses fascinating problems for particle astrophysics: how the primary particles are accelerated to these energies, how the primaries get here through the 2.7K…
Our understanding of the Universe today includes overwhelming observational evidence for the existence of an elusive form of matter that is generally referred to as dark. Although many theories have been developed to describe its nature,…
A high-energy neutrino telescope, such as the operating AMANDA detector, may detect neutrinos produced in sources, possibly active galactic nuclei or gamma-ray bursts, distant by a thousand megaparsecs. These sources produce mostly nu_e or…
Modern astrophysics, especially at GeV energy scales and above is a typical example where several disciplines meet: The location and distribution of the sources is the domain of astronomy. At distances corresponding to significant redshift…
Recent astronomical observations reveal that Active Galactic Nuclei (AGN) are sources of high-energy radiation. For example, the Fermi-LAT and Hess telescopes have detected gamma-ray emissions from the cores of several types of AGN's. Even…
Neutrinos are the best candidates to test the extreme Universe and ideas beyond the Standard Model of particle Physics. Once produced, neutrinos do not suffer any kind of attenuation by intervening radiation fields like the Cosmic Microwave…
We begin with a brief overview of highest-energy cosmic ray data, and the experiments which will perform neutrino astronomy. We then discuss two particle physics aspects of neutrinos. They are possible long-lifetime decay of the neutrino,…
Recent measurements of the properties of cosmic rays above 10^17 eV are summarized and implications on our contemporary understanding of their origin are discussed. Cosmic rays with energies exceeding 10^20 eV have been measured, they are…
The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, has been a mystery for over a century. Due to deflection in interstellar magnetic fields, cosmic rays from the Milky Way arrive at Earth from…
Blazar emission of gamma rays and cosmic ray production of gamma rays in gas-rich clusters have been proposed recently as alternative sources of the high energy extragalactic diffuse gamma ray background radiation. We show that these…
Astrophysics and cosmology can be used to test the standard model of particle physics under conditions and over distance and time scales not accessible to laboratory experiments. Most of the astrophysical observations are in good agreement…
Decaying topological defects, in particular cosmic strings, can produce a significant flux of high energy neutrinos, photons and cosmic rays. According to the prevailing understanding of cosmic string dynamics in an expanding Universe, the…
It has been argued that the observations of cosmic particles with energies in excess of $10^8$ TeV represent a puzzle. Its solution requires new astrophysics or new particle physics. We show that the latter is unlikely given that the scale…
Although high energy neutrino astronomy is a multidisciplinary science, gamma ray bursts have become the theoretical focus since recent astronomical observations revealed their potential as cosmic particle accelerators. This spotlight is…
Top-down models of cosmic rays produce more neutrinos than photons and more photons than protons. In these models, we reevaluate the fluxes of neutrinos associated with the highest energy cosmic rays in light of mounting evidence that they…