Evidence for a 36 ks phase modulation in the hard X-ray pulses from the magnetar 1E 1547.0-5408
Abstract
The Suzaku data for the highly variable magnetar 1E 1547.0-5408, obtained during the 2009 January activity, were reanalyzed. The 2.07 s pulsation, detected in the 15-40 keV HXD data, was found to exhibit phase modulation, which can be modeled by a sinusoid with a period of 36.0^{+4.5}_{-2.5}ks and an amplitude of 0.52 ± 0.14 s. While the effect is also seen in the 10-14 keV XIS data, the modulation amplitude decreased towards lower energies, becoming consistent with 0 below 4 keV. After the case of 4U 0142+61, this makes the second example of this kind of behavior detected from magnetars. The effect can be interpreted as a manifestation of torque-free precession of this magnetar, which is suggested to be prolately deformed under the presence of a strong toroidal field of ∼1016 G.
- Publication:
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Publications of the Astronomical Society of Japan
- Pub Date:
- June 2016
- DOI:
- 10.1093/pasj/psv097
- arXiv:
- arXiv:1501.07684
- Bibcode:
- 2016PASJ...68S..12M
- Keywords:
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- stars: individual: 1E 1547.0-5408;
- stars: magnetars;
- stars: magnetic fields;
- stars: neutron;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 18 pages, 12 figures, PASJ 10/2015 in press