The afterglow of GRB 010222:: A case of continuous energy injection

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 are naturally explained by a jet model with continuous energy injection. The electron energy 1.36% +/- 0.64% distribution then has p = 2.49 +/- 0.05, fully consistent with the expectation from detailed modeling of acceleration in relativistic shocks that, thus alleviating the p-problem.