[Cosmology sem.] Characterizing and treating observational systematics in galaxy clustering

par Martín Rodríguez Monroy

jeudi 25 mai 2023, 10:30 → 11:30 Europe/Paris

By combining the information provided by galaxy clustering, cosmic shear and galaxy-galaxy lensing into the 3x2pt probe measured on its third year (Y3) of observations, the Dark Energy Survey has obtained its last cosmology results, which represent one of the most precise tests of the standard cosmological model. In order to obtain tight and unbiased cosmological constraints, it is crucial to perform a thorough characterization of the systematic effects impacting these probes. From the point of view of galaxy clustering, observing conditions are one of the main sources of systematic error. The characterization and mitigation of these observational effects and the validation of the corrections applied has been one of the major challenges of the Year 3 analysis. Here, we present the different methodologies applied to deal with the observational systematics affecting the galaxy clustering signal during Y3, the lessons learnt and the improvements that are currently being applied for Year 6 and that will be essential for coming surveys such as Euclid and LSST.