Abstract

Contributed Talk - Splinter GalaxyClusters

Wednesday, 09 September 2026, 14:45   (MW-1050)

Weak-lensing mass calibration of SPT-3G clusters in Euclid Deep Field South Q1

F. Kleinebreil, H. Jansen, S. Grandis, T. Schrabback, G. Congendo, S.Bocquet, M. Kümmel, L. Beaumont
University of Innsbruck

According to the standard model of cosmology, galaxy clusters reside in massive dark matter halos, tracing the underlying large-scale structure of the Universe. Therefore, calibrating the mass distribution of galaxy clusters as a function of redshift provides a sensitive probe for cosmology and the growth of structures. One of the currently preferred tools to calibrate the mass scale of galaxy clusters is weak gravitational lensing (WL), which directly measures the gravitational mass of both – baryonic and dark matter – without relying on e.g. assumptions on gas physics of the intracluster medium. We present the first survey-level WL mass calibration of SPT-3G galaxy clusters using Euclid data. SPT-3G is the current third generation camera of the South Pole Telescope, a 10 m microwave telescope in Antarctica, that detects galaxy clusters via the Sunyaev-Zeldovic Effect as anisotropies in the Cosmic Microwave Background. The first SPT-3G cluster catalogue (Archipley+26) comprised observations of the Euclid Deep Field South, which also was part of the Euclid Quick Release 1 (Q1). Combined, these data sets provide a unique avenue to probe the cluster halo mass function to high redshifts, and a preview of the constraining power of upcoming stage-IV WL surveys. We calibrated stacked shear profiles of 67 SPT-3G clusters in EDFS up to redshift 1.6 using Euclid Q1 lensing data (Congedo+26, A&A submitted). As Euclid Early Release Observations (ERO) of Abell 2390 showed that Euclid's shape measurement capabilities will exceed the mission requirements by at least one magnitude (Schrabback+25), we also included the faint Euclid sources up to VIS magnitude 25.5 in this work. We performed custom calibrations for the WL source redshift distribution, shear bias, cluster member contamination, and a weak-lensing mass bias calibrated on hydro simulations. Finally, we analyzed the calibrated shear profiles through a Bayesian hierarchical model to determine the SPT limiting mass at different cluster redshifts, with the goal of providing the first cosmology results from Euclid data.