Messages from GRB 060218

Abstract

GRB 060218 is a watershed event. Statistically, its detection suggests that there is likely a distinct low-luminosity (LL) population of gamma-ray bursts (GRBs) whose event rate is much higher than that of conventional high-luminosity GRBs. This LL population may give significant contribution to the diffuse neutrino background flux at energies higher than 1016eV. The spectral lag of this burst is very long, and roughly follows the luminosity-lag relation of normal GRBs. This, along with the fact that it follows the Ep-Eiso relation as well, suggests that X-ray flashes (XRFs) are natural extension of GRBs in the softer regime and that GRBs and XRFs share the same radiation physics. We discuss how the broadband data pose strong constraints on possible models of the prompt emission of this GRB.