Efficiency of Acceleration of Relativistic Particles in the Crab Nebula

Abstract

The energy density of cosmic rays comparable to that of star light suggests the surprisingly high efficiency of converting the thermal energy into kinetic energy of relativistic particles. Although the storage of cosmic rays in the galactic magnetic field lowers the over-all efficiency, there must be some objects in which the acceleration is very efficient, since most of the stars, like the sun, are known to be rather poor producers of cosmic rays. An attempt is made to show on a semiquantitative basis that the high efficiency is really seen in the Crab nebula, the remnant of a supernova in 1054. Finally, the arguments are based on hypotheses, which seem to be plausible, that (a) the electromagnetic radiations are caused by the synchrotron radiation of relativistic electrons and (b) the so called rapid process of forming transuranic elements that took place in the explosion of the supernova in 1054.