We have investigated the X-ray emission from the shock-heated plasma of the Galactic supernova remnant Kesteven 69 withXMM-Newton. Assuming the plasma is at collisional ionization equilibrium, a plasma temperature and a column absorptionare found to be kT ~ 0.62 keV and NH ~ 2.85 ×1022 cm-2 respectively by imaging spectroscopy. Together with the deducedemission measure, we place constraints on its Sedov parameters.

Anomalous X-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strongmagnetic fields of >1014 Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energyreservoir to power the observed X-ray emission. High-energy emission above 0.3 MeV has never been detected despiteintensive search. Here, we present the possible Fermi Large Area Telescope (LAT) detection of γ-ray pulsations above 200MeV from the AXP, 1E 2259+586, which puts the current theoretical models of γ-ray emission mechanisms of magnetars intochallenge. We speculate that the high-energy γ-rays originate from the outer magnetosphere of the magnetar.