Improved Correlation between the Variability and Peak Luminosity of Gamma-Ray Bursts

Abstract

A new procedure for smoothing a gamma-ray burst (GRB) lightcurve and calculating its variability is presented. Applying the procedure to a sample of 25 long GRBs, we have obtained a very tight correlation between the variability and the peak luminosity. The only significant outlier in the sample is GRB 030329. With this outlier excluded, the data scatter is reduced by a factor of \sim 3 compared to that of Guidorzi et al. (2005), measured by the deviation of fit. Possible causes for the outlier are discussed.

9 pages, including 7 figure. Expanded as requested by referee. An error in Fig. 1 was corrected (the two 1-sigma lines in the old version were wrong). Accepted for publication by MNRAS