X-ray Vision

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Science  10 Dec 2010:
Vol. 330, Issue 6010, pp. 1457
DOI: 10.1126/science.330.6010.1457-b

In 2008, the Fermi Large Area Telescope detected a pulsar based solely on its gamma-ray pulsations. Now, using the XMM-Newton space-based telescope, Lin et al. and Caraveo et al. have revealed that this source, PSR J0007+7303, also pulsates in x-rays. Pulsars are magnetized, rapidly rotating neutron stars; like lighthouses, they appear to flash periodically as their beams of electromagnetic radiation cross our line of sight. For many decades, the vast majority of pulsars astronomers knew about were detected through their radio emission. PSR J0007+7303 was only the second radio-quiet pulsar to be detected in gamma rays; now it is also the second radio-quiet gamma-ray pulsar to show x-ray pulsations. These observations help build a more complete picture of this pulsar. The x-rays are believed to stem from both the heat of the neutron star's surface and from relativistic particles in the star's magnetosphere, which are also the origin of the gamma rays. In the case of PSR J0007+7303, the heat component appears to dominate; the x-ray pulsations possibly originate from a hot spot on the neutron star's surface, which is heated by return currents from the magnetosphere.

Astrophys. J. 725, L1; L6 (2010).

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