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Science 16 July 2004:
Vol. 305. no. 5682, pp. 376 - 379
DOI: 10.1126/science.1097173
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Reports

Phase-Resolved Spectroscopy of Geminga Shows Rotating Hot Spot(s)

P. A. Caraveo,1* A. De Luca,1 S. Mereghetti,1 A. Pellizzoni,1 G. F. Bignami2,3,1

Isolated neutron stars are seen in x-rays through their nonthermal and/or surface thermal emissions. X-ray Multimirror Mission–Newton observations of the Geminga pulsar show a 43–electron volt spectrum from the whole neutron star surface, as well as a power-law component above 2 kiloelectron volts. In addition, we have detected a hot (170 electron volts) thermal emission from an ~60-meter-radius spot on the pulsar's surface. Such a thermal emission, only visible at selected phase intervals, may be coming from polar hot spot(s), long thought to exist as a result of heating from magnetospheric accelerated particles. It may provide the missing link between the x-ray and gamma-ray emission of the pulsar.

1 Istituto di Astrofisica Spaziale e Fisica Cosmica, Consiglio Nazionale delle Ricerche, Via Bassini, 15-20133 Milano, Italy.
2 Centre d'Étude Spatiale des Rayonnements, Centre National de la Recherche Scientifique, Université Paul Sabatier, 9 Avenue du Colonel Roche, Toulouse, France.
3 Università di Pavia, Dipartimento Fisica Teorica e Nucleare, Via Ugo Bassi, 6 Pavia, Italy.

* To whom correspondence should be addressed. E-mail: pat{at}mi.iasf.cnr.it

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