High energy emission components in the short GRB 090510

Understand

We investigate the origin of the prompt and delayed emission observed in the short GRB 090510.

• We use the broad-band data to test whether the most popular theoretical models for gamma-ray burst emission can accommodate the observations for this burst.
• We first attempt to explain the soft-to-hard spectral evolution associated with the delayed onset of a GeV tail with the hypothesis that the prompt burst and the high energy tail both originate from a single process, namely synchrotron emission from internal shocks.
• Considerations on the compactness of the source imply that the high-energy tail should be produced in a late-emitted shell, characterized by a Lorentz factor greater than the one generating the prompt burst.