[Previous] | [Session 61] | [Next]
T. Stanev (Bartol Research Institute)
The observations of the highest energy cosmic rays, particles or nuclei of energy above 1020 eV, present several difficult problems. If these cosmic rays are accelerated in astrophysical shocks, similarly to the lower energy cosmic rays, these shocks should maintain microgauss magnetic fields on hundred kiloparsec scales. The astrophysical systems that contain these shocks have to be cosmologically nearby, because such high energy nuclei have energy loss distance of only few tens of Mpc in interactions on the microwave background and other radiation fields.
On the other hand the small world statistics of such events appear isotropic, without well defined source regions. This opens the possibility for exotic scenarios where the highest energy cosmic rays are generated at topological defects such as magnetic monopoles and cosmic strings. Several new generation experiments will start operating in the near future. The solution of the basic problems will also contribute to our knowledge of the large scale structure of the extragalactic magnetic fields.
This work is supported in part by NASA grant NAG5-7009