Abstract
The optical light curve of GRB 010222 exhibited one of the slowest decays of any gamma-ray burst to date. Its broadband properties have been difficult to explain with conventional afterglow models, as they require either the power-law index of the underlying electron energy distribution to be low, p < 2, or the outflow to be quasi-spherical, thus reviving the energy problem. We argue that the slow decay of GRB 010222 and a linear polarization of 1.36% ± 0.64% are naturally explained by a jet model with continuous energy injection. The electron energy distribution then has p = 2.49 ± 0.05, fully consistent with the expectation from detailed modeling of acceleration in relativistic shocks that p > 2, thus alleviating the "p-problem."
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Footnotes
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Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.