Spectral fitting of gamma-ray bursts

Their jets are thought to be powered by either the Blandford-Znajek (BZ) process or neutrino-dominated accretion flows (NDAFs), but discriminating between these mechanisms remains challenging. To address this, we proposed using the luminosity decay slope (d) of GRB light curves to distinguish between the BZ and NDAF mechanisms, thereby linking the light-curve morphology to the central engine physics.

By analysing 85 single-peaked GRBs with fast-rise, exponential-decay (FRED) profiles observed by Swift/BAT using 64 ms background-subtracted light curves, we fitted the decay slope (d) with the empirical Kocevski-Ryde-Liang (KRL) function and compared the results with theoretical predictions for the BZ (d~1.67) and the NDAF (d~3.7-7.8) mechanisms. We find that the decay slope (d) can differentiate central engine mechanisms, with 15 GRBs consistent with the BZ mechanism and 22 supporting the NDAF mechanism.