A Leptonic–hadronic Model for the Afterglow of Gamma-ray Burst 090510

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 3 × 1051 erg but two orders of magnitude larger than the absolute γ -ray energy. We also calculated the opacities for electron–positron pair production by γ -rays and found that TeV γ -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.