Cosmological parameters from pre-Planck CMB measurements: A 2017 update

We present cosmological constraints from the combination of the full mission nine-year WMAP release and small-scale temperature data from the pre-Planck Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) generation of instruments. This is an update of the analysis presented in Calabrese et al. [Phys. Rev. D 87, 103012 (2013)], and highlights the impact on $\mathrm{\Lambda }\mathrm{CDM}$ cosmology of a 0.06 eV massive neutrino—which was assumed in the Planck analysis but not in the ACT/SPT analyses—and a Planck-cleaned measurement of the optical depth to reionization. We show that cosmological constraints are now strong enough that small differences in assumptions about reionization and neutrino mass give systematic differences which are clearly detectable in the data. We recommend that these updated results be used when comparing cosmological constraints from WMAP, ACT and SPT with other surveys or with current and future full-mission Planck cosmology. Cosmological parameter chains are publicly available on the NASA’s LAMBDA data archive.

Figure 1

One-dimensional posterior distributions for the six basic $\mathrm{\Lambda }\mathrm{CDM}$ parameters as obtained in Calabrese et al. [1] and with this revised analysis. We also show a direct comparison with the constraints from the Planck baseline data set [18], analyzed with the same assumptions (see also Table 1).

Figure 2

Two-dimensional contour regions at 68% and 95% confidence for the matter density, ${\mathrm{\Omega }}_m$, and the amplitude of matter fluctuations on $8h^{-1}\mathrm{Mpc}$ scales, ${\sigma }_8$. A $1.5\sigma$ shift towards lower values of ${\sigma }_8$ is found in this revised analysis.