Monday

The abundance of galaxy clusters as a function of mass and redshift is one of the most promising probes for the large scale structure on the Universe, probing both the matter density, the amplitude of its fluctuations as well as the evolution of the Dark Energy components equation of state. The major limiting factor of such inference is the ability to reliably map the observables in which the clusters have been selected to the underlying mass of the host halos — called mass calibration. Over the last decades, weak gravitational lensing has been identified as the most robust method to perform mass calibration. We present an improved method (Grandis+21) that allows to determine the systematic error budget in weak lensing mass calibration by combining the matter distributions around massive halos predicted by large volume hydrodynamical structure formation simulations (Magneticum and TNG) with the calibration products of current wide photometric surveys (DES) used to measure the weak lensing signature. Comparison between different simulations suggests a 2% residual mass uncertainty, derived from comparison between different simulations. Observational uncertainties such as the accuracy of photometric redshift uncertainties, the choice of the observational cluster center, shape measurement accuracy and background selection lead to additional uncertainty of 2.5% at intermediate redshift 0.2z0.5 for the DES-Y3 survey, providing excellent constraining power from DES-Y3 WL calibrated SPT cluster number counts. We then also discuss the improvements on the simulations necessary to reach 1% mass accuracy for the upcoming Stage IV lensing surveys (Euclid, Rubin).