Temporal profiles and spectral lags of XRF 060218

Abstract

The spectral and temporal properties of the nonthermal emission of the nearby XRF 060218 in the 0.3-150 keV band are studied. We show that both the spectral energy distribution and the light-curve properties suggest the same origin of the nonthermal emission detected by Swift BAT and XRT. This event has the longest pulse duration and spectral lag observed to date among the known GRBs. The pulse structure and its energy dependence are analogous to typical GRBs. By extrapolating the observed spectral lag to the Compton Gamma Ray Observatory (CGRO) BATSE bands we find that the hypothesis that this event complies with the same luminosity-lag relation with bright GRBs cannot be ruled out at 2 σ significance level. These intriguing facts, along with its compliance with the Amati relation, indicate that XRF 060218 shares the similar radiation physics as typical GRBs. © 2006. The American Astronomical Society. All rights reserved.