HIGH-ENERGY PARTICLE-ACCELERATION BY EXPLOSIVE ELECTROMAGNETIC-INTERACTION IN AN ACCRETION DISK

BY examining electromagnetic field evolution occurring in an accretion disk around a compact object, we arrive at an explosive mechanism of particle acceleration. Flux-freezing in the differentially rotating disk causes the seed and/or generated magnetic field to wrap up tightly, becoming highly sheared and locally predominantly azimuthal in orientation. We show how asymptotically nonlinear solutions for the electromagnetic fields may arise in isolated plasma blobs as a result of the driving of the fluid equations by the accretion flow. These fields are capable of rapidly accelerating charged particles from the disk. Our results have implications for the hard component of astrophysical jets, for accretion disk coronae, and for cosmic rays. In particular, acceleration through the present mechanism from active galactic nuclei (AGNs) can give rise to energies beyond 10(20) eV. Such a mechanism may present an explanation for the extragalactic origin of the most energetic observed cosmic rays.