X-ray Studies of the Pulsar Wind Nebula Around PSR B0540-69

The pulsar wind nebula (PWN) surrounding the 50-ms pulsar B0540-69 in the Large Magellanic Cloud shares many properties with the Crab Nebula, the canonical Galactic PWN. We have used the ACIS instrument on the Chandra X-ray Observatory to perform spatially resolved spectroscopy of the PWN. The spectrum of the inner 10″ is characterized by a simple power law, with a spectral index that steepens strongly with radius. Outside the central 10″ the spectra also require a thermal component. This diameter corresponds to a shell detected in [OIII], suggesting that this shell represents a skin around the PWN, in analogy to the Crab. We infer the value of several key PWN parameters, including σ, the average ratio of electromagnetic to particle flux.