润色这段话：In terms of observation there is a plateau in X-ray evolution for many sGRBs citepBarthelmy2005Natur Lv2017ApJ Lv2020ApJL and follow $L_EM propto t^-1$ then have a deep decay phase $L_EM propto

In terms of observation, it has been found that there is a plateau in the X-ray evolution of many short gamma-ray bursts (sGRBs) \citep{Barthelmy2005Natur, Lv2017ApJ, Lv2020ApJL}. This plateau is followed by a deep decay phase where the electromagnetic luminosity ($L_{EM}$) follows a power law relation with time ($t$), i.e., $L_{EM} \propto t^{\alpha}$ $(\alpha < -3)$, after initially following $L_{EM} \propto t^{-1}$. These observations are consistent with the presence of a SMNS central engine and the relationship between the luminosity and time.