Volume 393, Number 2, October II 2002
|Page(s)||409 - 423|
|Section||Cosmology (including clusters of galaxies)|
|Published online||23 September 2002|
Time resolved spectral analysis of bright gamma ray bursts
SISSA/ISAS, Trieste - V. Beirut 2-4, 34014 Trieste, Italy
2 Osservatorio Astronomico di Brera, via Bianchi 46, Merate (LC), Italy
Corresponding author: G. Ghirlanda, email@example.com
Accepted: 27 June 2002
We present the time integrated and time resolved spectral analysis of a sample of bright bursts selected with from the BATSE archive. We fitted four different spectral models to the pulse time integrated and time resolved spectra. We compare the low energy slope of the fitted spectra with the prediction of the synchrotron theory [ predicting photon spectra softer than ] , and test, through direct spectral fitting, the synchrotron shock model. We point out that differences in the parameters distribution can be ascribed to the different spectral shape of the models employed and that in most cases the spectrum can be described by a smoothly curved function. The synchrotron shock model does not give satisfactory fits to the time averaged and time resolved spectra. Finally, we derive that the synchrotron low energy limit is violated in a considerable number of spectra both during the rise and decay phase around the peak.
Key words: gamma rays: bursts / methods: data analysis / radiation mechanisms: non–thermal
© ESO, 2002
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