Speaker
Description
We present cosmological constraints from the joint analysis of galaxy clustering and weak gravitational lensing ($3 \times 2$ pt) using the Dark Energy Survey Year 6 (DES Y6) data in harmonic space. In a nutshell, cosmological $3 \times 2$ point analysis is the joint analysis of $3$ 2-point correlation functions, galaxy clustering, galaxy-galaxy lensing and cosmic shear. This analysis utilizes over 140 million source galaxies and 9 million lens galaxies, covering approximately 5000 deg$^2$. The analysis in harmonic space using angular power spectra provide a natural framework for modeling survey geometry, scale cuts, and theoretical predictions. We measure the auto- and cross-correlations between galaxy shapes and positions across multiple tomographic redshift bins, constructing a comprehensive data vector that captures the statistical information of the large-scale structure. In a flat $\Lambda$CDM model,the combined $3 \times 2$ pt measurements yield a factor of two improvement in constraining power in the $\Omega_m$-$\sigma_8$ plane compared to DES Year 3. This presentation details the harmonic space methodology, validation against simulations, and the recovered cosmological results.