Giant Flare in SGR 1806-20 and Its Compton Reflection from the Moon

Abstract

We analyze the data obtained when the Konus-Wind gamma-ray spectrometer detected a giant flare in SGR 1806-20 on December 27, 2004. The flare is similar in appearance to the two known flares in SGR 0526-66 and SGR 1900+14 while exceeding them significantly in intensity. The enormous X-ray and gamma-ray flux in the narrow initial pulse of the flare leads to almost instantaneous deep saturation of the gamma-ray detectors, ruling out the possibility of directly measuring the intensity, time profile, and energy spectrum of the initial pulse. In this situation, the detection of an attenuated signal of Compton back-scattering of the initial pulse emission by the Moon with the Helicon gamma-ray spectrometer onboard the Coronas-F satellite was an extremely favorable circumstance. Analysis of this signal has yielded the most reliable temporal, energy, and spectral characteristics of the pulse. The temporal and spectral characteristics of the pulsating flare tail have been determined from Konus-Wind data. Its soft spectra have been found to contain also a hard power-law component extending to 10 MeV. A weak afterglow of SGR 1806-20 decaying over several hours is traceable up to 1 MeV. We also consider the overall picture of activity of SGR 1806-20 in the emission of recurrent bursts before and after the giant flare.

arXiv comment29 pages including 18 figures; to appear in Astronomy Letters, 2007, 33, p 1-18

References in corpus (13)

• An exceptionally bright flare from SGR1806-20 and the origins of short-duration gamma-ray bursts
• Gamma-Ray Observations of a Giant Flare from The Magnetar SGR 1806-20
• A giant, periodic flare from the soft gamma repeater SGR1900+14
• The Giant Flare of 1998 August 27 from SGR 1900+14: II. Radiative Mechanism and Physical Constraints on the Source
• Discovery of a New Soft Gamma Repeater, SGR 1627-41
• GEOTAIL observation of the SGR1806-20 Giant Flare: The first 600 ms
• Discovery of a Radio Source following the 27 December 2004 Giant Flare from SGR 1806-20
• The first giant flare from SGR 1806-20: observations with the INTEGRAL SPI Anti-Coincidence Shield
• A Giant Outburst from SGR 1900+14 Observed with the BeppoSAX Gamma Ray Burst Monitor
• Unusual Burst Emission from the New Soft Gamma Repeater SGR1627-41
• Konus catalog of SGR activity to 2000
• Constraints on the distance to SGR 1806-20 from HI absorption
• Observations of a possible new soft gamma repeater, SGR1801-23

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