The origin of prompt emission from gamma-ray bursts (GRBs) remains to be an open question. Correlated prompt optical and γ-ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the broadband GRB spectrum prompted the hypothesis of different emission mechanisms for the low- and high-energy radiations. We demonstrate that our multi-component model for GRB γ-ray prompt emission provides an excellent fit to GRB 110205A from optical to γ-ray energies. Our results show that the optical and highest γ-ray emissions have the same spatial and spectral origin, which is different from the bulk of the X- and softest γ-ray radiation. Finally, our accurate redshift estimate for GRB 110205A demonstrates promise for using GRBs as cosmological standard candles.
Bibliographical noteFunding Information:
We thank Takanori Sakamoto for the precious help and the referee for the useful comments that helped to improve the quality of this article. To complete this project, S.G. was supported by the NASA grants NNH11ZDA001N and NNH13ZDA001N, which were awarded to S.G. during cycles 5 and 7 of the NASA Fermi Guest Investigator Program. P.M. was supported by the NASA grant NNX13AH50G. J.G. and R. G. acknowledge support from the Israeli Science Foundation under grant No. 719/14. R.G. is supported by an Outstanding Postdoctoral Researcher Fellowship at the Open University of Israel.
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- acceleration of particles
- black hole physics
- distance scale
- gamma-ray burst: general
- radiation mechanisms: non-thermal
- radiation mechanisms: thermal