Abstract

Contributed Talk - Splinter GalaxyClusters   (MW-1050)

Unlocking the full potential of the eRASS:5 cluster catalog with weak-lensing observations from DES and DECADE

Tobias Mistele
Max Planck Institute for Extraterrestrial Physics

The first five SRG/eROSITA All-Sky Surveys (eRASS:5) have cumulatively produced the largest X-ray-selected and optically confirmed galaxy cluster catalog to date. I will present weak-lensing shear measurements of about 90% of the eRASS:5 clusters using weak-lensing observations from DES Y3 and DECADE in a combined area of over 9,000 deg^2. I will present significant improvements in the modeling of contamination from cluster member galaxies, allowing us to deal with the higher degree of noise and inhomogeneity in survey depth in DECADE as well as with systematics in the photo-z point estimates in both DES Y3 and DECADE. These shear measurements will enable strong constraints on cosmological parameters such as Ωm and σ8 by comparing the observed cluster abundance to the theoretical halo mass function. I will further present direct measurements of stacked 3D density profiles in the outskirts of the eRASS:5 clusters using on a new, non-parametric deprojection formula. These density profiles directly confirm the 1/r^3 decay predicted by LCDM, but we also detect intriguing behavior that may lie beyond traditional LCDM expectations.