Revisiting CMB constraints on Warm Inflation

Abstract: We revisit the constraints that Planck 2015 temperature, polarization and lensing data impose on the parameters of warm inflation. To this end, we study warm inflation driven by a single scalar field with a quartic self interaction potential in the weak dissipative regime. We analyse the effect of the parameters of warm inflation, namely, the inflaton self coupling $\lambda$ and the inflaton dissipation parameter $Q_P$ on the CMB angular power spectrum. We constrain $\lambda$ and $Q_P$ for 50 and 60 number of e-foldings with the full Planck 2015 data (TT, TE, EE + lowP and lensing) by performing a Markov-Chain Monte Carlo analysis using the publicly available code {\tt CosmoMC} and obtain the joint as well as marginalized distributions of those parameters. We present our results in the form of mean and 68 \% confidence limits on the parameters and also highlight the degeneracy between $\lambda$ and $Q_P$ in our analysis. From this analysis we show how warm inflation parameters can be well constrained using the Planck 2015 data.