Detection of a Compact X-Ray Source in the Supernova Remnant G29.6+0.1: A Variable Anomalous X-Ray Pulsar?

Abstract

We present follow-up observations of the serendipitously discovered 7 s X-ray pulsar AX J1845?0258, which displays characteristics similar to those observed in the anomalous X-ray pulsars (AXPs). We find a dramatic reduction in its 3–10 keV flux in both new ASCA and Rossi X-Ray Timing Explorer data sets.Within the pulsar's position error locus, we find a faint point source, AX J184453?025640, surrounded by an arc of diffuse X-ray emission. This arc is coincident with the southeast quadrant of the radio shell of the newly discovered supernova remnant G29.6?0.1, recently reported by Gaensler et al. Lack of sufficient flux from the source prevents us from confirming the 7 s pulsed emission observed in the bright state; hence, at present we cannot definitively resolve whether AX J1845?0258 and AX J184453?025640 are one and the same. If they are the same, then the peak- to-peak luminosity changes recorded for AX J1845?0258 may be larger than seen in other AXPs; closer mon- itoring of this pulsar might lead to a resolution on the mechanism that drives AXPs.