Giant bursts of soft gamma ray repeaters:
Reconnection events(?) in magnetars' magnetospheres

T. Terasawa

On December 27, 2004, plasma particle detectors aboard of the 
GEOTAIL spacecraft detected extremely strong signals of hard 
X ray photons (above 50 keV) from the giant burst at SGR1806-20, 
one of the several known magnetors, namely neutron stars with 
strong magnetic field beyond the quantum limit.  According to the
conventional model (Thompson and Dancan, 1995,1996,2001), this 
burst is interpreted as the result of magnetic energy release 
in the magnetars' magnetosphere where reconnection in the 
relativistic plasma should play the essential role.  I will 
summarized the observational data, and discuss their physical
implications.