The event GW170817/GRB 170817A , discovered via the successful joint observation of its gravitational wave radiation and its multi-wavelength electromagnetic counterparts , was the first definite “ smoking-gun ” from the merger of two neutron stars ( NSs ) .
However , the remnant of the merger remains unknown .
Piro et al .
recently claimed that a low-significance X-ray variability in GRB 170817A .
By systematically comparing the properties of variability in the afterglow of GRB 170817A and X-ray flares in GRB afterglows , we find that this X-ray variability seems to share similar statistical correlations with X-ray flares in GRB afterglows .
We further investigate several possible merger product scenarios to see whether they can produce the observed X-ray variability in GRB 170817A .
The first scenario invokes a stable magnetar as the central engine producing the later X-ray variability via differential rotation or fall-back accretion onto the NS .
The second scenario invokes a black hole as the central engine with a fall-back accretion process .
The final scenario is a central engine with a long-lived supra-massive NS .
We find that the first two scenarios have difficulty producing the later X-ray variability , which requires either an impractical NS magnetic field or an extraordinarily large stellar envelope and an extremely long accretion timescale .
However , the third scenario seems to be consistent with observations , and the later X-ray variability can be produced by the magnetosphere which is expelled following the collapse of the NS with a B _ { p } \in ( 3.6 , 13.5 ) \times 10 ^ { 13 } G .