Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing

Abstract

We present the first cosmology results from large-scale structure in the Dark Energy Survey (DES) spanning 5000 deg${}^2$. We perform an analysis combining three two-point correlation functions (3$\times$2pt): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) the cross-correlation of source galaxy shear with lens galaxy positions. The analysis was designed to mitigate confirmation or observer bias; we describe specific changes made to the lens galaxy sample following unblinding of the results. We model the data within the flat $\hat{I}›$CDM and $w$CDM cosmological models. We find consistent cosmological results between the three two-point correlation functions; their combination yields clustering amplitude $S_8=0.776_{-0.017}^{+0.017}$ and matter density $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.339_{-0.031}^{+0.032}$ in $\hat{I}›$CDM, mean with 68% confidence limits; $S_8=0.775_{-0.024}^{+0.026}$, $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.352_{-0.041}^{+0.035}$, and dark energy equation-of-state parameter $w=-0.98_{-0.20}^{+0.32}$ in $w$CDM. This combination of DES data is consistent with the prediction of the model favored by the Planck 2018 cosmic microwave background (CMB) primary anisotropy data, which is quantified with a probability-to-exceed $p=0.13$ to $0.48$. When combining DES 3$\times$2pt data with available baryon acoustic oscillation, redshift-space distortion, and type Ia supernovae data, we find $p=0.34$. Combining all of these data sets with Planck CMB lensing yields joint parameter constraints of $S_8=0.812_{-0.008}^{+0.008}$, $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.306_{-0.005}^{+0.004}$, $h=0.680_{-0.003}^{+0.004}$, and $\sum m_{\hat{I}}½<0.13\mathrm{eV}(95\%\mathrm{CL})$ in $\hat{I}›$CDM; $S_8=0.812_{-0.008}^{+0.008}$, $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.302_{-0.006}^{+0.006}$, $h=0.687_{-0.007}^{+0.006}$, and $w=-1.031_{-0.027}^{+0.030}$ in $w$CDM. (abridged)

See https://www.darkenergysurvey.org/des-year-3-cosmology-results-papers/ for the full DES Y3 3x2pt cosmology release. Matches version accepted in PRD