On ultra-high energy cosmic ray acceleration at the termination shock of young pulsar winds

Understand

Pulsar wind nebulae (PWNe) are outstanding accelerators in Nature, in the sense that they accelerate electrons up to the radiation reaction limit.

• Motivated by this observation, this paper examines the possibility that young pulsar wind nebulae can accelerate ions to ultra-high energies at the termination shock of the pulsar wind.
• We consider here powerful PWNe, fed by pulsars born with $\sim\,$millisecond periods.
• Assuming that such pulsars exist, at least during a few years after the birth of the neutron star, and that they inject ions into the wind, we find that protons could be accelerated up to energies of the order of the Greisen-Zatsepin-Kuzmin cut-off, for a fiducial rotation period $P\,\sim\,1\,$msec and a pulsar magnetic field $B_{\star}\,\sim\,10^{13}\,$G, implying a fiducial wind luminosity $L_{\rm p}\,\sim\,10^{45}\,$erg/s and a spin-down time $t_{\rm sd}\,\sim 3\times 10^7\,$s.