Gamma-Ray Burst Early Optical Afterglows: Implications for the Initial Lorentz Factor and the Central Engine

@article{Zhang2003GammaRayBE,
  title={Gamma-Ray Burst Early Optical Afterglows: Implications for the Initial Lorentz Factor and the Central Engine},
  author={Bing Zhang and Shiho Kobayashi and P{\'e}ter M{\'e}sz{\'a}ros},
  journal={The Astrophysical Journal},
  year={2003},
  volume={595},
  pages={950-954}
}
Early optical afterglows have been observed from GRB 990123, GRB 021004, and GRB 021211, which reveal rich emission features attributed to reverse shocks. It is expected that Swift will discover many more early afterglows. Here we investigate in a unified manner both the forward and the reverse external shock emission components, and introduce a straightforward recipe for directly constraining the initial Lorentz factor of the fireball using early optical afterglow data. The scheme is largely… Expand

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