Images of Bursting Sources of High-Energy Cosmic Rays: Effects of Magnetic Fields

Abstract

It has recently been shown that the highest energy cosmic rays (CRs) may originate in the same cosmological objects that produce γ-ray bursts. This model requires the presence of an intergalactic magnetic field (IGMF) to delay the arrival times of ~1020 eV CRs by 50 yr or longer relative to the γ-rays, of an amplitude that is consistent with other observational constraints. Sources of CRs coming from individual bursts should be resolved with the planned Auger experiment, with as many as hundreds of CRs for the brightest sources. We analyze here the apparent angular and energy distribution of CRs from bright sources below the pion production threshold (in the energy range 1019 eV < E < 4 × 1019 eV) expected in this model. This observable distribution depends on the structure of the IGMF: the apparent spectral width ΔE is small, ΔE/E 1%, if the intergalactic field correlation length λ is much larger than 1 Mpc, and large, ΔE/E = 0.3, in the opposite limit, λ 1 Mpc. The apparent angular size is also larger for smaller λ. If the sources of CRs we predict are found, they will corroborate the bursting model and provide us with a technique to investigate the structure of the IGMF.