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Prompt Ultraviolet-to-Soft-X-Ray Emission of Gamma-Ray Bursts: Application to GRB 031203?

Zhuo Li·Li-Ming Song
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Abstract

We discuss the prompt emission of GRBs, allowing for $γγ$ pair production and synchrotron self-absorption. The observed hard spectra suggest heavy pair-loading in GRBs. The re-emission of the generated pairs results in the energy transmission from high-energy gamma-rays to long-wavelength radiation. Due to strong self-absorption, the synchrotron radiation by pairs is in optically thick regime, showing a thermal-like spectral bump in the extreme-ultraviolet/soft X-ray band, other than the peak from the main burst. Recently, the prompt soft X-ray emission of GRB 031203 was detected thanks to the discovery of a delayed dust echo, and it seems to be consistent with the model prediction of a double-peak structure. The confirmation of the thermal-like feature and the double-peak structure by observation would indicate that the dominant radiation mechanism in GRBs is synchrotron rather than inverse-Compton radiation.

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Zhuo Li, Li-Ming Song. 2004-04-23. Prompt Ultraviolet-to-Soft-X-Ray Emission of Gamma-Ray Bursts: Application to GRB 031203?. https://doi.org/10.1086/422098

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