Discovery of X-ray pulsation from the geminga-like pulsar psr J2021+4026

L. C.C. Lin, C. Y. Hui, C. P. Hu, J. H.K. Wu, R. H.H. Huang, L. Trepl, J. Takata, K. A. Seo, Y. Wang, Y. Chou, K. S. Cheng

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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.

Original languageEnglish
Article numberL9
JournalAstrophysical Journal Letters
Issue number1
StatePublished - 10 Jun 2013


  • ISM: individual objects (G78.2+2.1)
  • X-rays: stars
  • gamma rays: stars
  • pulsars: individual (PSR J2021+4026)


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