中国科学院云南天文台机构知识库

The mono-frequency peak luminosity and the corresponding photon energy of the time-integrated (L-p(s), E-p(s)) and peak time (L-p(t), E-p(t)) nu f(nu) spectra were derived for a sample of 38 redshift-known Fermi GRBs by fitting the spectra with the Band function. It was found that E-p(t) is generally consistent with E-p(s), and L-p(t) is averagely three times larger than L-p(s). The slope of the L-p(t) - E-p(t), relation was consistent with that of the L-p(s) - E-p(s) relation. The photon indices in the peak time spectrum, particularly, the index of the low energy end was, were statistically larger than that in the time-integrated spectrum. These results indicate that L-p(s) and E-p(s) are dominated by L-p(t) and E-p(t) respectively. The difference of the spectral indices between the time-integrated and peak time spectra may be because of the overlap effect of a series of time-resolved spectra within a GRB. Our simulations, which were based on the observed spectral evolution and correlation between the energy flux and the peak energy within individual GRBs support our speculations. The L-p(t) - E-p(t) relation may be less contaminated by the overlap effect, and it would may be an intrinsic feature of radiation physics.