The SRG/eROSITA all-sky survey

Subaru/HSC-SSP weak-lensing mass measurements for eRASS1 galaxy clusters

¹ Physics Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
² Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
³ Core Research for Energetic Universe, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
⁴ Argelander-Institut für Astronomie (AIfA), Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁵ Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria
⁶ Department of Physics, National Cheng Kung University, No.1, University Road, Tainan City 70101, Taiwan
⁷ Center for Frontier Science, Chiba University, 1-33 Yayoi-cho, Inage-ku Chiba 263-8522, Japan
⁸ Department of Physics, Graduate School of Science, Chiba University, 1-33 Yayoi-Cho, Inage-Ku, Chiba 263-8522, Japan
⁹ Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141 Taipei 10617, Taiwan
¹⁰ Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany
¹¹ IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse, France
¹² INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Piero Gobetti 93/3, I-40129 Bologna, Italy
¹³ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, China

^⋆ Corresponding author: okabe@hiroshima-u.ac.jp

Received: 9 January 2025
Accepted: 12 June 2025

Abstract

We performed individual weak-lensing (WL) mass measurements for 78 eROSITA’s first All-Sky Survey (eRASS1) clusters in the footprint of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) S19A. We did not adopt priors on the eRASS1 X-ray quantities or assumption of the mass and concentration relation. In the sample, we found three clusters are misassociated with optical counterparts and 12 clusters are poorly fitted with an NFW profile. The average mass for the 12 poor-fit clusters changes from ∼ 10¹⁴ h₇₀⁻¹ M_⊙ to ∼ 2 × 10¹³ h₇₀⁻¹ M_⊙ when lensing contamination from surrounding mass structures is taken into account. The scaling relations between the true mass and cluster richness and X-ray count-rate agree well with the results of the eRASS1 western Galactic hemisphere region based on count-rate-inferred masses, which were calibrated with the HSC-SSP, DES, and KiDS surveys. We developed a Bayesian framework for inferring the mass-concentration relation of the cluster sample, explicitly incorporating the effects of weak-lensing mass calibration in the mass-concentration parameter space. The redshift-dependent mass and concentration relation is in excellent agreement with predictions of dark-matter-only numerical simulations and previous studies using X-ray-selected clusters. Based on the two-dimensional (2D) WL analysis, the offsets between the WL-determined centers and the X-ray centroids for 36 eRASS1 clusters with high WL S/N can be described by two Gaussian components. We find that the miscentering effect with X-ray centroids is smaller than that involving peaks in the galaxy maps. Stacked mass maps support a small miscentering effect, even for clusters with a low WL S/N. The projected halo ellipticity is ⟨ε⟩ = 0.45 at M₂₀₀ ∼ 4 × 10¹⁴ h₇₀⁻¹ M_⊙, which is in agreement with the results of numerical simulations and previous studies of clusters characterized by masses greater than twice the mass treated here.