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SGRJ 1550-5418 bursts detected with the fermi gamma-ray burst monitor during its most prolific activity

Van der Horst, A. J. and Kouveliotou, C. and Gorgone, N. M. and Kaneko Göğüş, Yuki and Baring, M. G. and Guiriec, S. and Göğüş, Ersin and Granot, J. and Watts, A. L. and Lin, L. and Bhat, P. N. and Bissaldi, E. and Chaplin, V. L. and Finger, M. H. and Gehrels, N. and Gibby, M. H. and Giles, M. M. and Goldstein, A. and Gruber, D. and Harding, A. K. and Kaper, L. and Von Kienlin, A. and Van der Klis, M. and McBreen, S. and Mcenery, J. and Meegan, C. A. and Paciesas, W. S. and Pe'er, A. and Preece, R. D. and Ramirez-Ruiz, E. and Rau, A. and Wachter, S. and Wilson-Hodge, C. and Woods, P. M. and Wijers, R. A. M. J. (2012) SGRJ 1550-5418 bursts detected with the fermi gamma-ray burst monitor during its most prolific activity. Astrophysical Journal, 749 (2). ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/749/2/122

Abstract

We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E-peak and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

Item Type:Article
Additional Information:Article Number: 122
Uncontrolled Keywords:pulsars: individual (SGR J1550-5418, 1E 1547.0-5408, PSR J1550-5418); stars: neutron; X-rays: bursts
Subjects:Q Science > QB Astronomy > QB460-466 Astrophysics
Q Science > QB Astronomy
ID Code:19038
Deposited By:Ersin Göğüş
Deposited On:17 May 2012 10:55
Last Modified:17 May 2012 16:32

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