Inflationary features and shifts in cosmological parameters from <i>Planck</i> 2015 data

Abstract

We explore the relationship between features in the Planck 2015 temperature and polarization data, shifts in the cosmological parameters, and features from inflation. Residuals in the temperature data from the best-fit power-law $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model at low multipole $\ensuremath{\ell}\ensuremath{\lesssim}40$ are mainly responsible for the high ${H}_{0}$ and low ${\ensuremath{\sigma}}_{8}{\mathrm{\ensuremath{\Omega}}}_{m}^{1/2}$ values when comparing the $\ensuremath{\ell}&lt;1000$ portion to the full data set. These same residuals are better fit to inflationary features with a $1.9\ensuremath{\sigma}$ preference for running of the running of the tilt or a stronger 99% C.L. local significance preference for a sharp drop in power around $k=0.004\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, relieving the internal tension with ${H}_{0}$. At $\ensuremath{\ell}&gt;1000$, the same in-phase acoustic residuals that drive the global ${H}_{0}$ constraints and appear as a lensing anomaly also favor running parameters which allow even lower ${H}_{0}$, but not once lensing reconstruction is considered. Polarization spectra are intrinsically highly sensitive to these parameter shifts, and even more so in the Planck 2015 TE data due to an anomalous suppression in power at $\ensuremath{\ell}\ensuremath{\approx}165$, which disfavors the best-fit ${H}_{0}$ $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ solution by more than $2\ensuremath{\sigma}$, and high ${H}_{0}$ value at almost $3\ensuremath{\sigma}$. Current polarization data also slightly enhance the significance of a sharp suppression of large-scale power but leave room for large improvements in the future with cosmic variance limited $E$-mode measurements.