Astron. Astrophys. Suppl. Ser. 138, 529-530
Send offprint request: E. Liang
Department of Space Physics and Astronomy, Rice University, 6100 S. Main, Houston, TX 77005-1892, U.S.A.
Received December 29, 1998; accepted March 30, 1999
We revisit the different physical interpretations of the spectral break in GRB continuum and the low energy turnover, especially at the beginning of pulses. We argue that optically thin synchrotron emission can be ruled out in many cases. Alternative models are discussed. We then concentrate on one paricularly attractive model: saturated Comptonization of soft photons. We summarize the various predictions of this model and highlight the critical tests of this model that may be provided by existing and future data.
Key words: gamma-rays: bursts -- gamma-rays: observations -- radiation mechanisms: non-thermal -- techniques: spectroscopic
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