Unusual burst emission from the new soft gamma repeater SGR 1627-41

In 1998 June-July, the Konus-Wind burst spectrometer observed a series of b ursts from the new soft gamma repeater SGR 1627-41. Time histories and ener gy spectra of the bursts have been studied, revealing fluences and peak flu xes in the ranges 3 x 10(-7) to 7.5 x 10(-6) ergs cm(-2) and 10(-5) to 10(- 4) ergs cm(-2) s(-1), respectively. One event, 18 June 6153.5 s UT, stands out dramatically from this series. Its fluence is similar to 7 x 10(-4) erg s cm(-2) and its peak flux is similar to 2 x 10(-2) ergs cm(-2) s(-1). Thes e values from a source at a distance of 5.8 kpc yield an energy output of s imilar to 3 x 10(42) ergs and a maximum luminosity of similar to 8 x 10(43) ergs s(-1) for isotropic emission, similar to the values for the famous 19 79 March 5 and 1998 August 27 events. In terms of energy, this event is ano ther giant outburst seen in a third soft gamma repeater! However, this very energetic burst differs significantly from the other giant outbursts. It e xhibits no separate initial pulse with a fast rise time, no extended tail, and no pulsations. It is rather similar to ordinary repeated bursts, but is a few hundred times stronger in intensity. According to the magnetar model by Thompson & Duncan, such a burst may be initiated by a strong starquake when a crust fracture propagates over the whole surface of a neutron star.