XMM-Newton and Chandra Observations of the Unidentified Fermi-LAT Source 3FGL J1016.5–6034: A Young Pulsar with a Nebula?

We report the discovery of a bright X-ray source in the XMM-Newton and Chandra X-Ray Observatory (Chandra) images of the unidentified Fermi-LAT source 3FGL J1016.5–6034. The XMM-Newton spectrum of the source is well fit by an absorbed blackbody+power-law model with a temperature kT = 0.20 ± 0.02 keV and photon index ? = 1.8 ± 0.1. Chandra resolves the same source into a point source (CXOU J101546.0–602939) and a surrounding compact nebula seen up to about 30? from the point source. The Chandra spectrum of the nebula can be described by an absorbed power law with ? = 1.7 ± 0.3 and is partly responsible for the nonthermal emission observed in the XMM-Newton spectrum. The XMM-Newton images also reveal faint extended emission on arcminute scales. These properties strongly suggest that the X-ray source and the accompanying extended emission are a newly discovered young pulsar with a pulsar wind nebula. We also analyze ?10 yr of Fermi-LAT data and find that the improved LAT source localization is consistent with the position of CXOU J101546.0–602939.