Constraining baryonic physics with DES Y1 and Planck data: Combining galaxy clustering, weak lensing, and CMB lensing

We constrain cosmology and baryonic feedback scenarios with a joint analysis of weak lensing, galaxy clustering, cosmic microwave background (CMB) lensing, and their cross-correlations (so-called $6\times 2$) using data from the Dark Energy Survey (DES) Y1 and the Planck satellite mission. Noteworthy features of our $6\times 2$ pipeline are: We extend CMB lensing cross-correlation measurements to a band surrounding the DES Y1 footprint (around 25% gain in pairs), and we develop analytic covariance capabilities that account for different footprints and all cross-terms in the $6\times 2$ analysis. We also measure the DES Y1 cosmic shear two-point correlation function (2PCF) down to $0{.}^{\prime }25$, but find that going below $2{.}^{\prime }5$ does not increase cosmological information due to shape noise. We model baryonic physics uncertainties via the amplitude of principal components (PCs) derived from a set of hydrosimulations. Given our statistical uncertainties, varying the first PC amplitude $Q_1$ is sufficient to model small scale cosmic shear 2PCF. For DES $Y1+\mathrm{Planck}$ $6\times 2$ we find $S_8=0.799\pm 0.016$, comparable to the $5\times 2$ result of DES $Y3+\mathrm{SPT}/\mathrm{Planck}$ $S_8=0.773\pm 0.016$. Combined with our most informative cosmology priors—baryon acoustic oscillation, big bang nucleosynthesis, type Ia supernovae, and Planck 2018 $\mathrm{EE}+\mathrm{lowE}$, we measure $S_8=0.817\pm 0.011$. Regarding baryonic physics constraints, our $6\times 2$ analysis finds $Q_1=2.8\pm 1.8$. Combined with the aforementioned priors, it improves the constraint to $Q_1=3.5\pm 1.3$. For comparison, the strongest feedback scenario considered in this paper, the cosmo-OWLS AGN ($\Delta T_{\mathrm{heat}}={10}^{8.7}K$), corresponds to $Q_1=5.84$.