A new supernova remnant coincident with the slow X-ray pulsar AX J1845-0258

We report on Very Large Array observations in the direction of the recently discovered slow X-ray pulsar AX J1845-0258. In the resulting images, we fi nd a 5' shell of radio emission; the shell is linearly polarized with a non thermal spectral index. We classify this source as a previously unidentifie d, young (<8000 yr) supernova remnant (SNR), G29.6+0.1, which we propose is physically associated with AX J1845-0258. The young age of G29.6+0.1 is th en consistent with the interpretation that anomalous X-ray pulsars (AXPs) a re isolated, highly magnetized neutron stars ("magnetars"). Three of the si x known AXPs can now be associated with SNRs; we conclude that AXPs are you ng (less than or equal to 10,000 yr) objects and that they are produced in at least 5% of core-collapse supernovae.