Kaneko, Yuki and Göğüş, Ersin and Kouveliotou, Chryssa and Granot, Jonathan and Ramirez-Ruiz, Enrico and van der Horst, Alexander J. and Watts, Anna L. and Finger, Mark H. and Gehrels, Neil and Pe'er, Asaf and van der Klis, Michiels and von Kienlin, Andreas and Wachter, Stefanie and Wilson-Hodge, Colleen A. and Woods, Peter M. (2010) Magnetar Twists: Fermi/Gamma-Ray Burst Monitor Detection of SGR J1550-5418. Astrophysical Journal, 710 (2). pp. 1335-1342. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100304-100001944
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Abstract
SGR J1550-5418 (previously known as AXP 1E 1547.0-5408 or PSR J1550-5418) went into three active bursting episodes in 2008 October and in 2009 January and March, emitting hundreds of typical soft gamma repeater bursts in soft gamma rays. The second episode was especially intense, and our untriggered burst search on Fermi/Gamma-ray Burst Monitor (GBM) data (8-1000 keV) revealed ~450 bursts emitted over 24 hr during the peak of this activity. Using the GBM data, we identified a ~150 s long enhanced persistent emission during 2009 January 22 that exhibited intriguing timing and spectral properties: (1) clear pulsations up to ~110 keV at the spin period of the neutron star (P ~ 2.07 s, the fastest of all magnetars); (2) an additional (to a power-law) blackbody component required for the enhanced emission spectra with kT ~ 17 keV; and (3) pulsed fraction that is strongly energy dependent and highest in the 50-74 keV energy band. A total isotropic-equivalent energy emitted during this enhanced emission is estimated to be 2.9 × 10^(40)(D/5 kpc)^2 erg. The estimated area of the blackbody emitting region of ≈0.046(D/5 kpc)^2 km^2 (roughly a few ×10^(–5) of the neutron star area) is the smallest "hot spot" ever measured for a magnetar and most likely corresponds to the size of magnetically confined plasma near the neutron star surface.
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| Additional Information: | © 2010 American Astronomical Society. Print publication: Issue 2 (2010 February 20); received 2009 December 11; accepted for publication 2009 December 22; published 2010 January 29. We thank the referee, Dr. F. Camilo, for his valuable comments. This publication is part of the GBM/Magnetar Key Project (NASA grant NNH07ZDA001-GLAST, PI: C. Kouveliotou). We thank G. L. Israel and A. Tiengo for providing the precise spin ephemeris and source distance, respectively, prior to their publication. Y.K. and E.G. acknowledge EU FP6 Transfer of Knowledge Project “Astrophysics of Neutron Stars” (MTKD-CT-2006-042722). J.G. gratefully acknowledges a Royal Society Wolfson Research Merit Award. E. R.-R. thanks the Packard Foundation for support. A.J.v.d.H. was supported by an appointment to the NASA Postdoctoral Program at the MSFC, administered by Oak Ridge Associated Universities through a contract with NASA. | ||||||||||||
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| Subject Keywords: | pulsars: individual (SGR J1550–5418, 1E 1547.0–5408, PSR J1550-5418); stars: neutron; X-rays: bursts | ||||||||||||
| Record Number: | CaltechAUTHORS:20100304-100001944 | ||||||||||||
| Persistent URL: | http://resolver.caltech.edu/CaltechAUTHORS:20100304-100001944 | ||||||||||||
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| Official Citation: | Magnetar Twists: Fermi/Gamma-Ray Burst Monitor Detection of SGR J1550-5418 Yuki Kaneko, Ersin Göğüş, Chryssa Kouveliotou, Jonathan Granot, Enrico Ramirez-Ruiz, Alexander J. van der Horst, Anna L. Watts, Mark H. Finger, Neil Gehrels, Asaf Pe'er, Michiels van der Klis, Andreas von Kienlin, Stefanie Wachter, Colleen A. Wilson-Hodge, and Peter M. Woods 2010 ApJ 710 1335-1342 doi: 10.1088/0004-637X/710/2/1335 | ||||||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||
| ID Code: | 17659 | ||||||||||||
| Collection: | CaltechAUTHORS | ||||||||||||
| Deposited By: | Jason Perez | ||||||||||||
| Deposited On: | 04 Mar 2010 22:53 | ||||||||||||
| Last Modified: | 26 Dec 2012 11:49 |
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