제목: Toward High-Information Cluster Weak-Lensing Cosmology: Mass Calibration, Triaxiality, Orientation, and Miscentering​

​​​​​​​​​​​​​​​​​​연사: Dr. Tae-hyeon Shin (Carnegie Mellon University)​​​

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일시: 2026년 6월 10일 수요일 11:30

장소: 과학관 638호​​​

Abstract:

​Galaxy clusters are powerful probes of cosmology, but their constraining power depends critically on accurate mass calibration and a detailed understanding of the astrophysical and observational systematics that enter cluster selection and weak-lensing measurements. Traditionally, stacked tangential shear analyses have provided a robust way to calibrate the mean mass scale of cluster samples. As current and next-generation surveys improve in statistical precision, however, cluster weak-lensing cosmology increasingly requires explicit modeling of projected halo structure, orientation, assembly bias, and miscentering.

In this talk, I will discuss a series of recent projects aimed at building a more structure-aware framework for cluster weak-lensing cosmology. I will first present weak-lensing mass calibration of ACT DR5 SZ-selected clusters using DES Year 3 data, including constraints on hydrostatic mass bias and its redshift dependence. I will then discuss weak-lensing measurements of cluster triaxiality using quadrupole shear signals, including recent LSST-DESC work that extends the formalism beyond leading order and implements it in the Cluster Lensing Mass Modeling (CLMM) software. I will also present an observational study of orientation and assembly bias using BCG shapes in SZ-selected clusters, and a Gaussian-mixture likelihood approach for modeling cluster miscentering beyond traditional stacked-profile analyses. Together, these studies point toward a next-generation cluster cosmology framework in which mass scale, halo shape, orientation, and centering are modeled as connected components of the weak-lensing signal rather than treated only as residual nuisance uncertainties.