Detection of an X-ray Pulsation for the Gamma-ray Pulsar Centered in CTA 1

TL;DR

This paper reports the detection of X-ray pulsations from the gamma-ray pulsar PSR J0007+7303, revealing different emission sites for X-ray and gamma-ray components and confirming its similarity to Geminga.

Contribution

First detection of X-ray pulsations from PSR J0007+7303, establishing its emission characteristics and comparison to Geminga.

Findings

X-ray pulsation period of ~315.87 ms consistent with gamma-ray period

X-ray and gamma-ray emissions originate from different sites

PSR J0007+7303 is the second radio-quiet gamma-ray pulsar with X-ray pulsations

Abstract

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.