Discovery of pulsed γ-rays from PSR J0034-0534 with the fermi large area telescope: A case for co-located radio and γ-ray emission regions

Millisecond pulsars (MSPs) have been firmly established as a class of ?-ray emitters via the detection of pulsations above 0.1?GeV from eight MSPs by the Fermi Large Area Telescope (LAT). Using 13 months of LAT data, significant ?-ray pulsations at the radio period have been detected from the MSP PSR J0034?0534, making it the ninth clear MSP detection by the LAT. The ?-ray light curve shows two peaks separated by 0.274 ? 0.015 in phase which are very nearly aligned with the radio peaks, a phenomenon seen only in the Crab pulsar until now. The ?0.1?GeV spectrum of this pulsar is well fit by an exponentially cutoff power law with a cutoff energy of 1.8 ? 0.6 ? 0.1?GeV and a photon index of 1.5 ? 0.2 ? 0.1, first errors are statistical and second are systematic. The near-alignment of the radio and ?-ray peaks strongly suggests that the radio and ?-ray emission regions are co-located and both are the result of caustic formation.