Discovery of X-Ray Pulsation from the Geminga-like Pulsar PSR J2021+4026
Cheng, K. S.; Takata, J.; Wang, Y.; Hui, C. Y.; Wu, J. H. K.; Lin, L. C. C.; Trepl, L.; Seo, K. A.; Hu, C. P.; Chou, Y.; Huang, R. H. H.
Taiwan, South Korea, Germany, Hong Kong SAR
Abstract
We report the discovery of an X-ray periodicity of ~265.3 ms from a deep XMM-Newton observation of the radio-quiet γ-ray pulsar, PSR J2021+4026, located at the edge of the supernova remnant G78.2+2.1 (γ-Cygni). The detected frequency is consistent with the γ-ray pulsation determined by the observation of the Fermi Gamma-ray Space Telescope at the same epoch. The X-ray pulse profile resembles the modulation of a hot spot on the surface of the neutron star. The phase-averaged spectral analysis also suggests that the majority of the observed X-rays have thermal origins. This is the third member in the class of radio-quiet pulsars with significant pulsations detected from both X-ray and γ-ray regimes.