Ultra-high-energy cosmic-ray acceleration by magnetic reconnection in newborn accretion-induced collapse pulsars

We here investigate the possibility that the ultra-high-energy cosmic-ray (UHECR) events observed above the Greisen-Zatsepin-Kuzmin (GZK) limit are mostly protons accelerated in reconnection sites just above the magnetosphere of newborn millisecond pulsars that are originated by accretion-induced collapse (AIC). We formulate the requirements for the acceleration mechanism and show that AIC pulsars with surface magnetic fields 10(12) G < B* less than or similar to 10(15) G and spin periods 1 ms less than or similar to P* < 60 ms are able to accelerate particles to energies greater than or equal to 10(20) eV. Because the expected rate of AIC sources in our Galaxy is very small (similar to 10(-5) yr(-1)), the corresponding contribution to the flux of UHECRs is negligible and the total flux is given by the integrated contribution from AIC sources produced by the distribution of galaxies located within the distance that is unaffected by the GZK cutoff (similar to 50 Mpc). We find that reconnection should convert a fraction xi greater than or equal to 0.1 of magnetic energy into UHECRs in order to reproduce the observed flux.