How unusual is XRF 060218 ?

TL;DR

This paper models the long-duration, chromatic X-ray light curves of XRF 060218 as resulting from off-axis scattering of primary radiation by baryonic material accelerated by the burst, offering a new explanation for its unusual features.

Contribution

It introduces a model where baryonic scattering explains the unique light curve features of XRF 060218, including its duration and spectral properties.

Findings

The model fits the observed light curves and predicts energy transfer to baryons.

Approximately 4×10^48 ergs are transferred to baryons by radiation pressure.

Emission below 3 KeV is identified as baryon contaminated fireball.

Abstract

Light curves are calculated for an off-axis observer due 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 $\sim 4\times 10^{48}$ ergs 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 {\it below} the Amati relation, is a baryon contaminated fireball.