Light curves are calculated for an off-axis observer due to the scattering of primary radiation by extended baryonic material. The unusually long duration and the chromaticity of the light curves above several KeV of XRF 060218 can be explained as a result of the acceleration of the baryonic scattering material by the primary radiation. The observed light curves by our model and detailed fits to the data are presented. The model predicts that ∼4 × 10 48 erg are put into accelerated, mildly relativistic baryons by the radiation pressure at large radii from the central engine. It is suggested that the emission below 3 KeV, which lies below the Amati relation, is a baryon contaminated fireball.
- Gamma-ray burst: general