A Unified Model for GRB Prompt Emission from Optical to $\gamma$-Rays:
  Exploring GRBs as Standard Candles
  The origin of prompt emission from gamma ray bursts remains to be an open
question. Correlated prompt optical and gamma-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 gamma-ray prompt emission provides an
excellent fit to GRB 110205A from optical to gamma-ray energies. Our results
show that the optical and highest gamma-ray emissions have the same spatial and
spectral origin, which is different from the bulk of the X- and softest
gamma-ray radiation. Finally, our accurate redshift estimate for GRB 110205A
demonstrates promise for using GRBs as cosmological standard candles.
