Speaker
Description
The observed narrow range of UHECR masses at any given energy has the perplexing implication that UHECR sources produce only a narrow range of rigidities. This motivates us to propose that most or all UHECRs are accelerated in the jets of BNS mergers. These jets have been shown to result from a gravitationally-driven dynamo, so the narrow range of BNS masses provides a rationale for the observed small source-to-source variance in maximum rigidities. As a bonus: BNS mergers produce r-process nuclei, naturally accounting for the highest energy UHECRs as having Z>26. Tests of this scenario will be discussed.
Time permitting, I will also report on work with L. Comisso and M.Muzio determining the power-law index and functional form of the spectral cutoff in fully-kinetic simulations of particle acceleration in magnetized turbulence. The predicted spectral shape gives a good accounting of the Auger spectrum and composition data, eliminating the need for an unphysically hard index as found when the exponential or softer cutoff predicted by diffuse shock acceleration theory is used.
