相关论文: On the ultra-high energy cosmic ray horizon
We will discuss the main relevant aspects of the physics of ultra high energy cosmic rays. After a short recap of the experimental evidences, we will review theoretical models aiming at describing the sources of these extremely energetic…
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…
The existence of cosmic ray particles up to the ultra-high energy limit (> 10^20 eV) is now beyond any doubt. The detection of cosmic particles with such energies imposes a challenge for the comprehension of their sources and nature. On one…
We present a brief introduction to the physics of Ultra High Energy Cosmic Rays (UHECRs), concentrating on the experimental results obtained so far and on what, from these results, can be inferred about the sources of UHECRs.
We discuss the basic features of the propagation of Ultra High Energy Cosmic Rays in astrophysical backgrounds, comparing two alternative computation schemes to compute the expected fluxes. We also discuss the issue of the transition among…
We discuss the basic difficulties in understanding the origin of the highest energy particles in the Universe - the ultrahigh energy cosmic rays (UHECR). It is difficult to imagine the sources they are accelerated in. Because of the strong…
The origin of cosmic rays is one of the major unresolved astrophysical questions. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely to be associated with the most energetic…
The origin of the particles in the highest energy end of the cosmic ray spectrum is discussed in the context of the wider problem of the origin of the whole cosmic radiation as observed at the Earth. In particular we focus our attention on…
A review of the status of the knowledge in the field of High-energy cosmic particles is presented. The spectrum, arrival direction distribution and composition measurements are summarized, together with some implications for the…
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…
Large-scale accretion shocks around massive clusters of galaxies, generically expected in hierarchical scenarios of cosmological structure formation, are shown to be potential sources of the observed ultrahigh energy cosmic rays (UHECRs) by…
We review the main experimental evidences on ultra high energy cosmic rays and their implications in the physics of these extremely energetic particles, also in connection with dark matter and cosmology. We discuss the basis of theoretical…
The observation of neutrinos from cosmic accelerators will be revolutionary. High energy neutrinos are closely connected to ultrahigh energy cosmic rays and their sources. Cosmic ray sources are likely to produce neutrinos and the…
Cosmic rays have been observed up to energies $10^8$ times larger than those of the best particle accelerators. Studies of astrophysical particles (hadrons, neutrinos and photons) at their highest observed energies have implications for…
Cosmic-rays with energies exceeding 10^{19} eV are referred to as Ultra High Energy Cosmic Rays (UHECRs). The sources of these particles and their acceleration mechanism are unknown, and for many years have been the issue of much debate.…
Ultra-high-energy (UHE) cosmic rays (CRs) of energies $\sim (10^{18}-10^{20})~{\rm eV}$, accelerated in violent astrophysical environments, interact with cosmic background radiation fields via photo-hadronic processes, leading to strong…
The origin of the highest energy cosmic rays is still unknown. The discovery of their sources will reveal the workings of the most energetic astrophysical accelerators in the universe. Current observations show a spectrum consistent with an…
Recent measurements of the spectrum and composition of ultrahigh energy cosmic rays suggest that their extragalactic sources may be accelerating heavy nuclei in addition to protons. This can suppress the cosmogenic neutrino flux relative to…
It is likely that ultra-high energy cosmic rays contain a significant component of heavy or intermediate mass nuclei. The propagation of ultra-high energy nuclei through cosmic radiation backgrounds is more complicated than that of protons…
A fundamental question that can be answered in the next decade is: WHAT IS THE ORIGIN OF THE HIGHEST ENERGY COSMIC PARTICLES? The discovery of the sources of the highest energy cosmic rays will reveal the workings of the most energetic…