The interpretation of the multi-wavelength afterglow emission of short GRB 140903A

GRB 140903A, a short duration $\gamma -$ray burst (SGRB) detected by {\it Swift}, is characterized by its long-lasting radio emission among SGRBs. In addition to the $\sim {10}^6$ s radio afterglow emission, the afterglow of GRB 140903A displays a plateau from ${10}^3$ s to $7\times {10}^3$ s in the X-rays. In this work, we attribute the X-ray plateau to the energy injection into the decelerating blast wave and then model the later radio/optical/X-ray afterglow emission within the standard fireball afterglow model. The afterglow emission has been well reproduced with reasonable physical parameters, including a jet half-opening angle $\sim 0.05$. We also compare the physical properties of SGRBs with and without radio afterglow detections and find that nearby SGRBs are brighter and easier to be detected in radio. Such a phenomena has been interpreted within the afterglow model.