UHECRs from magnetic reconnection in relativistic jets

TL;DR

This paper proposes that magnetic reconnection in relativistic jets of active galactic nuclei and gamma-ray bursts can efficiently accelerate ultra-high energy cosmic rays, reaching energies up to 10^{20} eV.

Contribution

It introduces a mechanism for UHECR acceleration via magnetic reconnection in jets, independent of the dissipation process details, and quantifies achievable energies for protons and iron nuclei.

Findings

Protons can reach energies up to 10^{20} eV in GRB and powerful AGN jets.

Iron nuclei can reach similar energies in moderate luminosity AGN jets.

Magnetic reconnection can serve as an efficient acceleration process for UHECRs.

Abstract

Ultra-high energy cosmic rays (UHECRs) may be produced in active galactic nuclei (AGN) or gamma-ray burst (GRB) jets. I argue that magnetic reconnection in jets can accelerate UHECRs rather independently of physical processes in the magnetic dissipation region. First order Fermi acceleration can efficiently take place in the region where the unreconnected (upstream) magnetized fluid converges into the reconnection layer. I find that protons can reach energies up to E~10^{20} eV in GRB and powerful AGN jets while iron nuclei can reach similar energies in AGN jets of more moderate luminosity.