DETECTION OF AN X-RAY PULSATION FOR THE GAMMA-RAY PULSAR CENTERED IN CTA 1

We report the detection of X-ray pulsations with a period of ~315.87 ms from the 2009 XMM-Newton observation for the radio-quiet gamma-ray pulsar, LAT PSR J0007+7303, centered in the supernova remnant CTA 1. The detected pulsed period is consistent with the gamma-ray periodicity at the same epoch found with the Fermi Gamma-ray Space Telescope. The broader sinusoidal structure in the folded light curve of the X-ray emission is dissimilar to that of the gamma-ray emission, and the phase of the peak is about 0.5 shifting from the peak in the gamma-ray bands, indicating that the main component of the X-rays originates from different sites of the pulsar. We conclude that the main component of the X-ray pulsation is contributed by the thermal emission from the neutron star. Although with a significantly different characteristic age, PSR~J0007+7303 is similar to Geminga in emission properties of X-rays and gamma-rays; this makes PSR J0007+7303 the second radio-quiet gamma-ray pulsar with detected X-ray pulsations after Geminga.
7 pages, 4 figures and 1 table; accepted by ApJL