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[51.04] Diagnosing Magnetars with Spectral Line Features

A. Ibrahim (NASA/GSFC & GWU), J. Swank (NASA/GSFC), W. Parke (GWU)

Evidence of magnetars associated with Soft Gamma Repeaters and Anomalous X-Ray Pulsars has accumulated over the years, including the extremely energetic and short burst durations, the long spin period and high spin-down, and also lack of evidence for a binary companion of a remnant accretion disk. Nevertheless, the determination of magnetars' most important parameter, the magnetic field strength, remained indirect for the past decade. With the Proportional Counter Array on board the Rossi X-ray Timing Explorer, we have recently discovered a 5 keV absorption feature in the burst spectra of SGR 1806-20. Consistent with proton cyclotron resonance, the feature provided a direct measurement of a magnetar-strength field and implied constraints on the mass and radius of the source. Here we outline our result and present further analysis and interpretation of new data.

The author(s) of this abstract have provided an email address for comments about the abstract: alaa@milkyway.gsfc.nasa.gov

Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.