DES Y3 cosmic shear down to small scales: constraints on cosmology and baryons

Understand

We present the first analysis of cosmic shear measured in DES Y3 that employs the entire range of angular scales in the data.

• To achieve this, we build upon recent advances in the theoretical modelling of weak lensing provided by a combination of $N$-body simulations, physical models of baryonic processes, and neural networks.
• Specifically, we use BACCOemu to model the linear and nonlinear matter power spectrum including baryonic physics, allowing us to robustly exploit scales smaller than those used by the DES Collaboration.
• We show that the additional data produce cosmological parameters that are tighter but consistent with those obtained from larger scales, while also constraining the distribution of baryons.