The power spectra of two types of long-duration γ-ray bursts

We have studied the averaged power density spectra (PDSs) of two classes of long-duration gamma-ray bursts in the recent classification by Balastegui et al. (2001) based on neural network analysis. Both PDSs follow a power law over a wide frequency range with approximately the same slope, which indicates that a process with a self-similar temporal property may underlie the emission mechanisms of both. The two classes of bursts are divided into groups according to their brightness and spectral hardness respectively and each groupʹs PDS was calculated. For both classes, the PDS is found to flatten both with increasing burst brightness and with increasing hardness.