  We model multiwavelength afterglow data from the short Gamma-Ray Burst (GRB)
090510 using a combined leptonic-hadronic model of synchrotron radiation from
an adiabatic blast wave. High energy, >100 MeV, emission in our model is
dominated by proton-synchrotron radiation, while electron-synchrotron radiation
dominates in the X ray and ultraviolet wavelengths. The collimation-corrected
GRB energy, depending on the jet-break time, in this model could be as low as
3e51 erg but two orders of magnitude larger than the gamma-ray energy. We also
calculated the opacities for electron-positron pair production by gamma rays
and found that TeV gamma rays from proton-synchrotron radiation can escape the
blast wave at early time, and their detection can provide evidence of a
hadronic emission component dominating at high energies.
