Related papers: GZK Photons Above 10 EeV
The flux of neutrinos and photons originating from cosmic ray interactions with the interstellar medium in the galaxy is calculated based on current models for high energy particle interactions. The contribution from a possible dark matter…
Ultra high energy protons accelerated at the shocks causing gamma ray bursts photoproduce pions, and then neutrinos in situ. I consider here the sources of losses in this process, namely adiabatic and synchrotron losses by both pions and…
Fast-spinning newborn pulsars are intriguing candidate sources of ultrahigh energy cosmic rays (UHECRs). The acceleration of particles with a given composition in a fraction of the extragalactic pulsar population can give a consistent…
The baryonic mass composition of ultrahigh energy ($\gtrsim 10^{18}$ eV) cosmic rays (UHECRs) at injection accompanied by their interactions on universal photon backgrounds during propagation directly governs the UHECR flux on the Earth.…
Astronomy at the highest energies observed must be performed by studying neutrinos rather than photons because the universe is opaque to photons of these energies. By making observations of neutrinos with energies above 10 EeV one can…
Energetics of the ultrahigh-energy cosmic rays (UHECRs) generated in the universe is crucial for pinning down their candidate sources. Using the recent Auger data on UHECR spectra, we calculate the UHECR energy generation rate density for…
We present results of a recent work on the reaction mechanism of $\eta n$ photoproduction off the neutron in the range of $ \sqrt{s} \approx 1.5 - 1.9$ GeV and discuss the role of various nucleon resonances listed in the Particle Data Group…
In a recent letter [1] with the same title, Farrar and Piran offered an explanation for the near isotropy of the arrival directions [2] of ultrahigh energy cosmic rays (UHECRs) and the apparent absence [3] of the so called `GZK cutoff' in…
The discoveries of the GZK cutoff with the HiRes and Auger Observatories and the discovery by Auger of clustering of >~60 EeV ultra-high energy cosmic rays (UHECRs) towards nearby <~75 Mpc) AGNs along the supergalactic plane establishes the…
Measurements of the arrival directions of cosmic rays have not revealed their sources. High energy neutrino telescopes attempt to resolve the problem by detecting neutrinos whose directions are not scrambled by magnetic fields. The key…
If neutrinos are a significant contributor to the matter density of the universe, then they should have $\sim$ eV mass and cluster in galactic (super) cluster halos, and possibly in galactic halos as well. It was noted in the early 1980's…
A new method to derive an upper limit on photon primaries from small data sets of air showers is developed which accounts for shower properties varying with the primary energy and arrival direction. Applying this method to the…
We demonstrate that a population of Active Galactic Nuclei (AGN) can describe the observed spectrum of ultra-high-energy cosmic rays (UHECRs) at and above the ankle, and that the dominant contribution comes from low-luminosity BL Lacs. An…
The flux of cosmic rays beyond the GZK cutoff ($\sim 10^{20}$ eV) may be explained through their production by ultra high energy cosmic neutrinos, annihilating on the relic neutrino background, in the vicinity of our galaxy. This process is…
Ultrahigh-energy cosmic rays passing through the central region of the Galaxy interact with starlight and the infrared photons. Both nuclei and protons generate secondary fluxes of photons and neutrinos on their passage through the central…
Under the assumption that some part of the observed highest energy cosmic rays consists of protons originating from cosmological distances, we derive bounds on the associated flux of neutrinos generated by inelastic processes with the…
We show that the deep expected in the diffuse photon spectrum above the threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic…
The apparent lack of suitable astrophysical sources for the observed highest energy cosmic rays (UHECRs) within $\approx 20$ Mpc is the "GZK Paradox". We constrain representative models of the extra-galactic magnetic field structure by…
Ultra-high energy cosmic rays interacting with the radiation fields in the universe cause electromagnetic cascades resulting in a flux of extragalactic gamma rays, detectable to some 100 GeV. Recent precise measurements of the extragalactic…
The propagation of UHECR nuclei for A=1 (protons) to A=56 (iron) from cosmological sources through extragalactic space is discussed in the first lecture. This is followed in the second and third lectures by a consideration of the generation…