Origin of the highest energy cosmic rays and the Galactic halo

The origin of the highest energy cosmic rays, particularly of these with primary energies E > 10(20) eV, is a puzzle. Both hypotheses, Galactic and extragalactic run into troubles: the former - because of an expected large anisotropy, the latter one - because of energy losses on the microwave background. Even an 'intermediate' hypothesis, that particles are produced by some particle objects (e.g. radiogalaxies, AGN's) relatively nearby (closer than some tens of Mpc) has difficulties as there are no such objects visible (Sigl et al. 1994). Here we are continuing our earlier work (Giller and Zielinska 1995, 1996, 1997), where we had been considering a possibility that our own Galaxy (in particular the Galactic Centre) could be the origin site of these high energy particles. Some conditions, however, would have to occur, which have been not often taken into consideration. These are - a/ a very large magnetic halo (several tens of kiloparsecs) and b/ a time dependent c.r. activity of the Galactic Centre. In our earlier papers we have shown that under the above conditions the problem of anisotropy is greatly reduced, if not lifted. We consider, however, that in the halo, there was practically only an irregular field, with an average value B-in = 2 mu G. In this paper we adopt a more realistic halo field, with a regular component in the disc and in the halo and consider a smaller halo (20 kpc).