REPROCESSING OF THE VHE AND UHE PHOTONS IN THE MAGNETOSPHERE OF HERCULES-X-1

For over twenty years numerous claims have been made about positive de tections of high energy radiation from several X-ray binaries by means of both Cherenkov light detectors and particle detectors. If real, th ose findings require incorporation of episodic relativistic processes into the conventional 'thermal' picture of these objects. We calculate the transfer of high energy photons through the magnetic field of an accreting neutron star taking as an example Her X-1 - a prime candidat e for a high-energy gamma-ray source. In some models such photons orig inate episodically in the pi(0)-decay process in outer parts of the ob ject's magnetosphere. They may, however, be subject to substantial abs orption due to presence of a strong magnetic field. With the help of M onte Carlo simulations we follow the development and propagation of el ectron-positron pair cascades initiated by one-photon pair creation. I n the case of a dipolar magnetic field the pi(0)-decay photons can esc ape freely but only within a very narrow cone with an opening angle of similar to 1 degrees. Otherwise the resulting cascade spectra have hi gh energy cut-offs ranging from similar to 1 TeV to similar to 10 TeV. We conclude that Her X-1 is an unlikely source of PeV radiation unles s very special conditions are met. At energies below similar to 1 TeV we expect an enhancement of the photon flux in comparison with the 'op tically thin' case (i.e. when one-photon absorption is neglected). The refore the object may be occasionally seen with the atmospheric Cheren kov technique. We also address the question of theoretical photon spec tra in the MeV and GeV bands in the context of the recent experiments like COMPTEL and EGRET.