Motivating by the discovery of association between GW 170817 and sGRB 170817A , we present a comprehensive analysis for sGRBs observed with Fermi/GBM in 9 operation years and study the properties of sGRB 170817A -like events .
We derive a catalog of 275 typical sGRBs and 48 sGRB 170817A-like weak events from the GBM data of 2217 GRBs .
We visibly identify two patterns of their light curve , single episode ( Pattern I , 61 % of the SGRBs ) and multiple episodes ( Pattern II , 39 % of the SGRBs ) .
Their duration distribution shows a tentative bimodal feature .
Their spectra can be fitted with a cutoff power-law model , except for 4 sGRBs , and the spectral indices normally distribute at \Gamma = 0.69 \pm 0.40 .
Their E _ { p } values show a tentative bimodal distribution with peaks at 145 keV and 500 keV .
No correlation among T _ { 90 } , E _ { p } , and \Gamma is found .
GRB 170817A is a soft , weak sGRB with E _ { p } = 124 \pm 106 keV , L _ { iso } = ( 5.67 \pm 4.65 ) \times 10 ^ { 46 } ~ { } erg~ { } s ^ { -1 } , and E _ { iso } = ( 3.23 \pm 2.65 ) \times 10 ^ { 46 } ~ { } erg .
It follows the E _ { iso } - E _ { p } relation of typical short GRBs .
Its lightcurve is of Pattern II .
Two lightcurve patterns , together with the potential two components in the E _ { p } and T _ { 90 } distributions , we suspect that the current sample may include two distinct types of sGRBs from different progenitors .
sGRB 170817A-like events may be from NS-NS mergers and those sGRBs with a Pattern I lightcurve may be from another distinct type of compact binary .