X-ray Pulsations from the Radio-quiet Gamma-ray Pulsar in CTA 1
Caraveo, P. A.; Bignami, G. F.; Marelli, M.; Ray, P. S.; Saz Parkinson, P. M.; De Luca, A.; Kanbach, G.
Italy, United States, Germany
Abstract
Prompted by the Fermi-LAT discovery of a radio-quiet gamma-ray pulsar inside the CTA 1 supernova remnant, we obtained a 130 ks XMM-Newton observation to assess the timing behavior of this pulsar. Exploiting both the unprecedented photon harvest and the contemporary Fermi-LAT timing measurements, a 4.7σ single-peak pulsation is detected, making PSR J0007+7303 the second example, after Geminga, of a radio-quiet gamma-ray pulsar also seen to pulsate in X-rays. Phase-resolved spectroscopy shows that the off-pulse portion of the light curve is dominated by a power-law, non-thermal spectrum, while the X-ray peak emission appears to be mainly of thermal origin, probably from a polar cap heated by magnetospheric return currents, pointing to a hot spot varying throughout the pulsar rotation.
Based on observations with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the USA (NASA).