Top panel: Break frequency resulting from the fit as a function of time. The expected behavior is overplotted with a solid line in the case of a wind environment and with dashed and dot-dashed lines in the case of ISM. The vertical shaded line represents the assumed deceleration time. Bottom panel: Peak flux in the spectra as a function of time. The expected behavior as a function of time for the wind environment is constant, while that for the ISM is plotted in dashed lines.