Chandra and rxte observations of 1E 1547.0-5408: Comparing the 2008 and 2009 outbursts

C. Y. Ng, V. M. Kaspi, R. Dib, S. A. Olausen, P. Scholz, T. Güver, F. Zel, F. P. Gavriil, P. M. Woods

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34 Scopus citations


We present results from Chandra X-ray Observatory and Rossi X-ray Timing Explorer (RXTE) observations of the magnetar 1E 1547.0-5408 (SGR J1550-5418) following the source's outbursts in 2008 October and 2009 January. During the time span of the Chandra observations, which covers days 4 through 23 and days 2 through 16 after the 2008 and 2009 events, respectively, the source spectral shape remained stable in the Chandra band, while the pulsar's spin-down rate in the same span in 2008 increased by a factor of 2.2 as measured by RXTE. This suggests decoupling between the source's spin-down and radiative changes, hence between the spin-down-inferred magnetic field strength and that inferred spectrally. The lack of spectral variation during flux decay is surprising for models of magnetar outbursts. We also found a strong anti-correlation between the phase-averaged flux and the pulsed fraction in the 2008 and 2009 Chandra data, but not in the pre-2008 measurements. We discuss these results in the context of the magnetar model.

Original languageEnglish (US)
Article number131
JournalAstrophysical Journal
Issue number2
StatePublished - Mar 10 2011


  • X-rays: bursts
  • pulsars: individual (1E 1547.0?5408, PSR J1550?5418, SGR J1550?5418)
  • stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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