Identification of CXOU J171405.7-381031 as a New Magnetar with XMM-Newton

We observed the 3.8s pulsar CXOU J171405.7-381031 with XMM-Newton, and discovered a significant (P) over dot of 6.40 +/- 0.05 x 10(-11) s s(-1) from this source for the first time, with the aid of archival Chandra data. The characteristic age (950 yr), the magnetic field strength (5 x 10(14)G), and the spin-down luminosity (4.5 x 10(34) erg s(-1)) derived from P and (P) over dot lead us to conclude that CXOU J171405.7-381031 should be identified as a new magnetar. The obtained characteristic age indicates that CXOU J171405.7-381031 is the youngest among all known anomalous X-ray pulsars, and is consistent with the age estimated from the thermal X-rays of the associated supernova remnant. The ratio between the 2-10 keV luminosity and the spin-down luminosity is almost unity, which implies that CXOU J171405.7-381031 is the key source to connect magnetars with traditional radio pulsars.