Discovery of a Possible Anomalous X-Ray Pulsar in the Small Magellanic Cloud

Abstract

We report the serendipitous detection of a previouslyunreported pulsar from the direction of the Small Magellanic Cloud usingdata from the Chandra X-Ray Observatory. Because of its luminosity(~1.5�1035 ergs s-1), its near lack of variability for morethan 20 yr, and its very soft spectrum, we propose that it is ananomalous X-ray pulsar (AXP). Data from the ROSAT PSPC in conjunctionwith the Chandra data give a period, P, of 5.44 s and a spin-downtime, P/P, of 11 kyr. If this is a correct identification, it willbe the first extragalactic AXP and the fastest yet discovered.