Evidence of Superdiffusive Transport of Electrons Accelerated at Interplanetary Shocks

Abstract

We study the transport properties of energetic electrons accelerated at corotating interaction regions in the solar wind considering the possibility of anomalous diffusion. It is shown that the particle time decay has a power-law behavior when a non-Gaussian propagator, appropriate for superdiffusive transport, is assumed for particles accelerated at a propagating shock. Looking at shock events detected by the Ulysses spacecraft at 5 AU, we found that 42-290 keV electron time profiles are well fitted by a power law corresponding to superdiffusive transport, i.e., <Δx²(t)>~t^α, with α=1.02-1.38. This implies that particle propagation in the heliosphere can be intermediate between normal diffusion and ballistic motion.