GRB afterglows: Deep Newtonian phase and its application

Gamma-ray burst afterglows have been observed for months or even years in a few cases. It is worth noting that at such late stages, the remnants should have entered the deep Newtonian phase, during which the majority of shockaccelerated electrons will no longer be highly relativistic. To calculate the afterglows, we must assume that the electrons obey a power law distribution according to their kinetic energy, not simply the Lorentz factor