INTERNAL LUMINOSITY DISTRIBUTION OF BRIGHT GAMMA-RAY BURSTS AND ITS RELATION TO DURATION AND SPECTRAL HARDNESS

We present first results from a comprehensive investigation into the d istribution of luminosity within the 50 brightest cosmic gamma-ray bur sts detected by the Burst and Transient Source Experiment (BATSE). The internal luminosity function psi(L) is defined such that the quantity psi(L)dL represents the fraction of total emission time during which the burst possesses a luminosity between L and L + dL. For these brigh test bursts, the psi(L) functions are quasi-power-law-like and decreas e in amplitude with increasing luminosity. Through investigation of bo th individual psi(L) distributions and data from the ensemble of burst s, we demonstrate a high probability for correlation between the shape of the internal luminosity function as measured by the average logari thmic slope and the burst duration as measured by the T-90 parameter a nd, with lower significance, between the shape of psi(L) and the burst photon-fluence spectral index. We furthermore demonstrate a correlati on between burst hardness ratio and duration in these brightest bursts which is opposite to that of the entire gamma-ray burst ensemble.