In search of a source for the 320 EeV Fly's Eye cosmic ray

Abstract

The 320 EeV air shower detected by the Fly's Eye poses an important problem. Careful analysis of pathlength limitations for the possible particle types due to cosmic background radiation verifies that the particle very likely traveled less than 50 Mpc from its source. The best candidates for accelerating particles to such high energies are the very powerful radiogalaxies, however they are all more than 100 Mpc distant. Our search finds no likely source within 50 Mpc in the direction from which the particle arrived. This prompts consideration of less likely astrophysical sources, like M82, as well as non-standard mechanisms like cosmic string annihilation. It is also conceivable that the air shower was produced by some non-standard particle whose pathlength is unlimited because it does not interact with the cosmic background radiation. A less radical alternative is that relatively strong magnetic fields deflected the particle's path through a large angle, so it could have originated at a nearby radiogalaxy at an earlier time of strong activity.

Uncorrelated Far Active Galactic Nuclei Flaring with Their Delayed Ultra High Energy Cosmic Rays Events

“…In summary on years 1991-2000, up to HiRes results, we were all believing that UHECR could overcome somehow the GZK cut off: this is because some of the most energetic [2] UHECR were uncorrelated with nearby (GZK distance) sources and because AGASA didn't show the GZK cut off. To face this over-GZK possibility few of us [9] suggested the presence of relic dark neutrino halos with a rest eVs masses, able to convert far AGN UHE ZeV neutrino energy by ν ZeV +ν relic scattering within a few Mpc ν relic halo, with energy at center of mass at Z boson resonance value; the Z ultra-relativistic decay may eject later on p ,p, n,n secondaries that could finally shine and shower on Earth's atmosphere as UHECR from far (above GZK cut off) Universe edges.…”

“…Since 25 years and up to now, after the early Fly's Eye event [2] (as well as the maximal, more and more puzzling, unbeaten 3 · 10 20 eV energetic event), after Akeno Giant Air Shower Array (AGASA) decade of records [3,4], the HiRes observation of a UHECR cut off [5], and the more recent hundreds of PAO and TA records [6][7][8], some (or let say most) of the UHECR are still mainly spread. In summary on years 1991-2000, up to HiRes results, we were all believing that UHECR could overcome somehow the GZK cut off: this is because some of the most energetic [2] UHECR were uncorrelated with nearby (GZK distance) sources and because AGASA didn't show the GZK cut off.…”

Observations and implications of the ultrahigh-energy cosmic rays

“…To reach an energy of 3ϫ10 20 eV is clearly a challenge. Elbert and Sommers (1995) made a detailed survey of source possibilities for the 3ϫ10 20 -eV event detected by the Fly's Eye group (Bird et al, 1993) and calculated that nearby radio galaxies, such as CenA, could be the source only if the extragalactic magnetic field was about 0.1 to 0.5 G, much higher than currently supposed. Additionally Sigl, Lemoine, and Biermann (1999) have speculated that an energy spectrum and arrival direction distribution consistent with the data could be obtained if the magnetic field in the local supercluster were 0.1 G. Thus two pieces of astrophysical understanding would need revision to explain the events: the parameters in the lobes of radio galaxies and the strength of the magnetic field in the local supercluster.…”

“…The predictions for sources at constant distances 64 and 16 Mpc are also shown. To explain the present energy spectrum and uniform arrival direction distribution in the highest-energy region with a limited number of nearby active galactic nucleus hot spots, the intergalactic magnetic field may be required to be much stronger than 10 Ϫ9 G (see, for example, Elbert and Sommers, 1995).…”

High energy neutrinos from astrophysical accelerators of cosmic ray nuclei

“…Starbursts, galaxies undergoing an episode of largescale star formation, have also been proposed as sources of ultra-high energy cosmic rays [50]. These environments feature strong infrared emission by dust associated with high levels of interstellar extinction, strong UV spectra from the Lyman α emission of hot OB stars, and considerable radio emission produced by recent supernova remnants.…”