Assessing the Effects of the Uncertainty in Reheating Energy Scale on Primordial Spectrum and CMB

The details of reheating energy scale $\rho_{reh}$ is largely uncertain today, independent of inflation models. This would induce uncertainty in predicting primordial spectrum. Such uncertainty could be very large, especially for spectra with large running $n_S$. We find that for some inflation models with a large $d\ln n_S(k)/d\ln k$, $\rho_{reh}$ could be highly restricted by current CMB observations.