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An X-ray Pulsar with a Superstrong Magnetic Field in the Soft Gamma-Ray Repeater SGR1806-20Soft gamma-ray repeaters (SGRs) emit multiple, brief (approximately O.1 s) intense outbursts of low-energy gamma-rays. They are extremely rare; three are known in our galaxy and one in the Large Magellanic Cloud. Two SGRs are associated with young supernova remnants (SNRs), and therefore most probably with neutron stars, but it remains a puzzle why SGRs are so different from 'normal' radio pulsars. Here we report the discovery of pulsations in the persistent X-ray flux of SGR1806-20, with a period of 7.47 s and a spindown rate of 2.6 x 10(exp -3) s/yr. We argue that the spindown is due to magnetic dipole emission and find that the pulsar age and (dipolar) magnetic field strength are approximately 1500 years and 8 x 10(exp 14) gauss, respectively. Our observations demonstrate the existence of 'magnetars', neutron stars with magnetic fields about 100 times stronger than those of radio pulsars, and support earlier suggestions that SGR bursts are caused by neutron-star 'crust-quakes' produced by magnetic stresses. The 'magnetar' birth rate is about one per millenium, a substantial fraction of that of radio pulsars. Thus our results may explain why some SNRs have no radio pulsars.
Document ID
19990007784
Document Type
Reprint (Version printed in journal)
Authors
Kouveliotou, C. (NASA Marshall Space Flight Center Huntsville, AL United States)
Dieters, S. (NASA Marshall Space Flight Center Huntsville, AL United States)
Strohmayer, T. (Universities Space Research Association Huntsville, AL United States)
vanParadijs, J. (NASA Marshall Space Flight Center Huntsville, AL United States)
Fishman, G. J. (NASA Marshall Space Flight Center Huntsville, AL United States)
Meegan, C. A. (NASA Marshall Space Flight Center Huntsville, AL United States)
Hurley, K. (California Univ. Berkeley, CA United States)
Kommers, J. (Massachusetts Inst. of Tech. Cambridge, MA United States)
Smith, I. (Rice Univ. Houston, TX United States)
Frail, D. (National Radio Astronomy Observatory Socorro, NM United States)
Murakami, T. (Tokyo Univ. Sagamihara, Japan)
Date Acquired
September 6, 2013
Publication Date
May 21, 1998
Publication Information
Publication: Nature
Volume: 393
Subject Category
Astrophysics
Report/Patent Number
NAS 1.15:208282
NASA/TM-1998-208282
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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