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Fermi/gamma-ray burst monitor observations of SGR J0501+4516 bursts

Lin, Lin and Kouveliotou, Chryssa and Baring, Matthew G. and van der Horst, Alexander J. and Guiriec, Sylvain and Woods, Peter M. and Göğüş, Ersin and Kaneko, Yuki and Scargle, Jeffrey and Granot, Jonathan and Preece, Robert and von Kienlin, Andreas and Chaplin, Vandiver and Watts, Anna L. and Wijers, Ralph A. M. J. and Zhang, Shuang Nan and Bhat, Narayan and Finger, Mark H. and Gehrels, Neil and Harding, Alice and Kaper, Lex and Kaspi, Victoria and Mcenery, Julie and Meegan, Charles A. and Paciesas, William S. and Pe'er, Asaf and Ramirez-Ruiz, Enrico and van der Klis, Michiel and Wachter, Stefanie and Wilson-Hodge, Colleen (2011) Fermi/gamma-ray burst monitor observations of SGR J0501+4516 bursts. Astrophysical Journal, 739 (2). ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/739/2/87

Abstract

We present our temporal and spectral analyses of 29 bursts from SGR J0501+4516, detected with the gamma-ray burst monitor on board the Fermi Gamma-ray Space Telescope during 13 days of the source's activation in 2008 (August 22-September 3). We find that the T(90) durations of the bursts can be fit with a log-normal distribution with a mean value of similar to 123 ms. We also estimate for the first time event durations of soft gamma repeater (SGR) bursts in photon space (i.e., using their deconvolved spectra) and find that these are very similar to the T(90) values estimated in count space (following a log-normal distribution with a mean value of similar to 124 ms). We fit the time-integrated spectra for each burst and the time-resolved spectra of the five brightest bursts with several models. We find that a single power law with an exponential cutoff model fits all 29 bursts well, while 18 of the events can also be fit with two blackbody functions. We expand on the physical interpretation of these two models and we compare their parameters and discuss their evolution. We show that the time-integrated and time-resolved spectra reveal that E(peak) decreases with energy flux (and fluence) to a minimum of similar to 30 keV at F = 8.7 x 10(-6) erg cm(-2) s(-1), increasing steadily afterward. Two more sources exhibit a similar trend: SGRs J1550-5418 and 1806-20. The isotropic luminosity, L(iso), corresponding to these flux values is roughly similar for all sources (0.4-1.5 x 10(40) erg s(-1)).

Item Type:Article
Additional Information:Article Number: 87
Uncontrolled Keywords:pulsars: individual (SGR J0501+4516); X-rays: bursts
Subjects:Q Science > QB Astronomy > QB460-466 Astrophysics
Q Science > QC Physics
ID Code:17382
Deposited By:Ersin Göğüş
Deposited On:16 Nov 2011 10:39
Last Modified:18 Nov 2011 20:27

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