Scale-invariance in soft gamma repeaters

Zhe Chang, Hai-Nan Lin, Yu Sang, Ping Wang

Published 2017-02-20Version 1

The statistical properties of soft gamma repeater SGR J1550--5418 are investigated carefully. We find that the cumulative distributions of fluence, peak flux and duration can be well fitted by the bent power law, while the cumulative distribution of waiting time follows the simple power law. In particular, the probability density functions of fluctuations of fluence, peak flux, and duration have a sharp peak and fat tails, which can be well fitted by the $q$-Gaussian function. The $q$ values keep approximately steady for different scale intervals, indicating a scale-invariant structure of soft gamma repeaters. Those results support that the origin of soft gamma repeaters is crustquake of neutron star with extremely strong magnetic fields.