Detection of the energetic pulsar PSR B1509-58 and its pulsar wind nebula in MSH 15-52 using the Fermi-large area telescope

We report the detection of high-energy γ-ray emission from the young and energetic pulsar PSR B1509 - 58 and its pulsar wind nebula (PWN) in the composite supernova remnant G320.4 - 1.2 (aka MSH 15 - 52). Using 1 yr of survey data with the Fermi-Large Area Telescope (LAT), we detected pulsations from PSR B1509 - 58 up to 1GeV and extended γ-ray emission above 1GeV spatially coincident with the PWN. The pulsar light curve presents two peaks offset from the radio peak by phases 0.96 ± 0.01 and 0.33 ± 0.02. New constraining upper limits on the pulsar emission are derived below 1GeV and confirm a severe spectral break at a few tens ofMeV. The nebular spectrum in the 1-100GeV energy range is well described by a power law with a spectral index of (1.57 ± 0.17 ± 0.13) and a flux above 1GeV of (2.91 ± 0.79 ± 1.35) × 10^-9cm^-2s^-1. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. The LAT spectrum of the nebula connects nicely with Cherenkov observations, and indicates a spectral break betweenGeV and TeV energies.