PRELIMINARY INVESTIGATION TO TEST EXTRAGALACTIC HYPOTHESIS FOR GAMMA-RAY BURSTS

Recent observations of CGRO satellite challenged the almost universall y accepted galactic origin of gamma-ray bursts and have revived the ex tragalactic, cosmological models. This hypothesis should imply some va riations of the morphological and energetic characteristics of the wea ker events to which we think the farthest ones might belong. The exist ence of such variations due to the cosmological red-shift should be te sted. In this paper we examine the possible correlations between tempo ral morphology of the gamma-ray bursts, peak intensity and photon ener gy spectra when the red-shift effects do not yet occur. We examine the peak intensities and the energy spectral-hardness distribution versus rise times for events observed by previous space missions, with a log N-log S shape free of cosmological effects. The results of this analy sis suggest that a wide range of values of the temporal and spectral c haracteristic parameters is an intrinsic property of the sources.