Large Torque Variations in Two Soft Gamma Repeaters

  title={Large Torque Variations in Two Soft Gamma Repeaters},
  author={Peter M. Woods and Chryssa Kouveliotou and Ersin Gougus and Mark H. Finger and Jean Hebb Swank and Craig B. Markwardt and Kevin Hurley and Michiel van der Klis Nsstc and Usra and NASA-MSFC and Uah and NasaGsfc and Ucb and University of Amsterdam},
  journal={The Astrophysical Journal},
We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of ~4, which persist for several months. Using long-baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR. The… 
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Variable spin-down in the soft gamma repeater SGR 1900+14 and correlations with burst activity
We have analyzed Rossi X-ray Timing Explorer Proportional Counter Array observations of the pulsed emission from SGR 1900+14 during 1996 September, 1998 June-October, and early 1999. Using these
Temporal and Spectral Characteristics of Short Bursts from the Soft Gamma Repeaters 1806–20 and 1900+14
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We report the detection of large flux changes in the persistent X-ray flux of soft gamma repeater (SGR) 1900+14 during its burst active episode in 1998. Most notably, we find a factor of ~700
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Soft γ-ray repeaters are transient sources of high-energy photons; they emit sporadic and short (about 0.1 s) bursts of ‘soft’ γ-rays during periods of activity, which are often broken by long
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The soft gamma repeater SGR 1900+14 became active on 2001 April 18 after about 2 years of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited
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The reappearance of persistent X-ray emission from SGR 1900+14 within one day of the August 27 event provides strong evidence that the persistent emission is not powered by accretion, and is attributed to continued particle heating in the active region of that outburst.