Cosmic rays, stellar evolution and supernova physics

Abstract

Most cosmic rays are thought to be accelerated by the shocks of supernova explosions of very massive stars. Here, we review one quantitative proposal, which predicted the spectral slopes, bend and cutoff about the cosmic ray spectrum across the spectral bend or “knee” near 3×10 15 eV in 1993. Many of the specific predictions have now been verified, and so it may be appropriate to investigate the consequences of that proposal. The successful fit to the cosmic ray data across the knee suggests: (1) very massive stars, above about 20–25 solar masses all converge to a common final state; (2) the supernova explosion of these very massive stars is caused by a combination of rotation, magnetic fields and the gravitational potential, just as proposed by Bisnovatyi-Kogan [Astron. Zh. (Sov. Astron.) 47 (1970) 813], based on an earlier suggestion by Kardashev [Astron. Zh. 41 (1964) 807]; (3) their stellar winds as well as the explosion provide the main injection of magnetic fields into the interstellar medium; (4) the explosive energy of these supernovae is about 10 52 erg; (5) the explosion is extremely anisotropic, which may unify several classes of observed supernova types; (6) γ-ray bursts may be the ultimate version of such an explosion in the case the collapse leads to a black hole; and (7) it is plausible that the luminosity of the supernova integrated over all aspect angles is also the same for all these massive star explosions, leading to (8) a possibly very bright standard candle, if we could just find a correction for the extreme asphericity. This may solve the problem of what the mechanism of supernova explosions is for very massive stars, where most cosmic rays and magnetic fields come from, and may also point the way to a unifying scheme for supernova explosions and γ-ray bursts.