Chasing cosmic inflation: constraints for inflationary models and reheating insights (2408.03321v2)

Abstract: We investigate the impact of different choice of prior's range for the reheating epoch on cosmic inflation parameter inference in light of cosmic microwave background (CMB) anisotropy measurements from the {\em Planck} 2018 legacy release in combination with BICEP/Keck Array 2018 data and additional late-time cosmological observations such as uncalibrated Type Ia supernovae from the Pantheon catalogue, baryon acoustic oscillations and redshift space distortions from SDSS/BOSS/eBOSS. Here, we explore in particular the implications for the combination of reheating and inflationary-model parameter space considering $R+R^2$ inflation and a broad class of $\alpha$-attractor and D-brane models. Propagating the uncertainties due to an unknown reheating phase, these inflationary models completely cover the $n_{\rm s}$-$r$ parameter space allowed by {\em Planck} and BICEP/Keck data and represent good targets for future CMB and large-scale structure experiments. We perform a Bayesian model comparison of inflationary models, taking into account the reheating uncertainties assuming a conservative but accurate modelling of inflationary predictions. $R+R^2$ inflation, T-model $\alpha$-attractor inflation for $n=1$, E-model $\alpha$-attractor inflation for $n=1/2$, and KKLT inflation for $p=5$ are the better performing models, with none being preferred at a statistically significant level.