Gamma-Ray Bursts and their Power Spectrum

Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density (PSD). Reanalyzing the expanded data, we have found a) the power-law in the PSD comes from the outline of the burst profile rather than fluctuations in short time scale. b) Although the power indices of the average PSD distribute around the value -1.67 with relatively small dispersion, the indices of individual PSD vary from burst to burst with large dispersion: the value -1.67 is given simply by averaging PSD whose indices are widespread