Capability of Searching for Kilonova Associated with a Short Gamma-ray Burst by SVOM

Abstract: In spite of the importance of studying the cosmic generation of heavy elements through the r-process, the detection of kilonova resulted from a merger of neutron star binaries is still a challenge task. In this paper, we show that the Visible Telescope (VT) onboard the on-going SVOM space mission is powerful for identifying kilonova candidates associated with short gamma-ray bursts (SGRBs) up to a distance of 600Mpc. A significant color variation, turn blue and then turn red, is revealed by calculating the light curves in both red and blue channels of VT by a linear combination of an afterglow and an associated kilonova. The maximum color variation is as high as $\sim0.5-1$ mag, which is far larger than the small photometry error of $\sim0.2$ mag of VT for a point source with a brightness of 23 mag. Up to a distance of 600Mpc, $\sim1-2$ kilonova candidates per year are predicted to be identified by VT.