Abstract
We revisit the saturated Compton cooling model of gamma-ray burst pulse decay in the context of cosmological scenarios. We find that for pulse duration of ~1 s, this model is consistent with Gpc distance if the Compton cooling plasma is a relativistically expanding thin shell of bulk Lorentz factor ≥102, radius ~1015 cm, thickness ≤1011-1012 cm, comoving lepton density ≥1013 cm-3 and is dominated by a thermal population of keV comoving temperature, with less than a few percent nonthermal population.