CaltechAUTHORS
Published August 2025 | Version Published
Journal Article Open

CHEX-MATE: The impact of triaxiality and orientation on Planck SZ cluster selection and weak lensing mass measurements

Creators

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon Institut de Recherche sur les Lois Fondamentales de l'Univers
  • 3. ROR icon Smithsonian Astrophysical Observatory
  • 4. ROR icon Korea Advanced Institute of Science and Technology
  • 5. ROR icon University of Geneva
  • 6. INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, I-40129, Bologna, Italy
  • 7. ROR icon INFN Sezione di Bologna
  • 8. ROR icon University of Modena and Reggio Emilia
  • 9. ROR icon Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
  • 10. ROR icon University of Manchester
  • 11. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 12. ROR icon University of Bristol
  • 13. ROR icon INFN Sezione di Genova
  • 14. ROR icon Sapienza University of Rome
  • 15. ROR icon University of Paris
  • 16. ROR icon Research Institute in Astrophysics and Planetology
  • 17. ROR icon Trieste Astronomical Observatory
  • 18. ROR icon Institute for Fundamental Physics of the Universe
  • 19. ROR icon University of Michigan–Ann Arbor

Abstract

Context. Galaxy cluster abundance measurements are a valuable tool for constraining cosmological parameters, such as the mass density (Ωm) and the density fluctuation amplitude (σ8). Wide-area surveys detect clusters based on observables, such as the total integrated Sunyaev-Zel’dovich effect signal (YSZ) in the case of Planck. Quantifying the survey selection function is necessary for cosmological analyses, with completeness representing the probability of detecting a cluster as a function of its intrinsic properties, such as YSZ and an angular scale θ500.

Aims. We determine the completeness of the Planck-selected CHEX-MATE cluster catalog using mock observations of clusters with triaxial shapes and random orientations, with physically-motivated distributions of axial ratios. From these mocks, we derive the distribution of shapes and orientations of the detected clusters, along with any associated bias in weak-lensing-derived mass (MWL) due to this orientation-dependent selection (denoted as 1 − bχ).

Methods. Employing a Monte Carlo method, we injected triaxial cluster profiles into random positions within the Planck all-sky maps and subsequently determined the completeness as a function of both geometry and SZ brightness. This result was then used to generate 1000 mock CHEX-MATE cluster catalogs. We computed MWL for these mock CHEX-MATE clusters and for equal-sized samples of randomly selected clusters with similar mass and redshift distributions.

Results. Cluster orientation impacts completeness, with a higher probability of detecting clusters elongated along the line of sight (LOS). This leads to 1 − bχ values of 0−4% for CHEX-MATE clusters relative to a random population. The largest increase in MWL is observed in the lowest-mass objects, which are most impacted by orientation-related selection bias.

Conclusions. Clusters in Planck SZ-selected catalogs are preferentially elongated along the LOS and have an average bias in MWL relative to randomly selected cluster samples. This bias is relevant for upcoming SZ surveys such as CMB-S4, and should be considered for surveys utilizing other probes for cluster detection, such as Euclid.

Copyright and License

© The Authors 2025. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

This research was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #565 (Multi-Wavelength Studies of the Culmination of Structure Formation in the Universe). H.S., J.S., A.G. and J.K. were supported by NASA Astrophysics Data Analysis Program (ADAP) Grant 80NSSC21K1571. SE, MS, MR acknowledges the financial contribution from the contracts Prin-MUR 2022 supported by Next Generation EU (M4.C2.1.1, n.20227RNLY3 The concordance cosmological model: stress-tests with galaxy clusters). MS acknowledges the financial contributions from contract INAF mainstream project 1.05.01.86.10 and INAF Theory Grant 2023: Gravitational lensing detection of matter distribution at galaxy cluster boundaries and beyond (1.05.23.06.17). SE, MR acknowledges the financial contributions from the European Union’s Horizon 2020 Programme under the AHEAD2020 project (grant agreement n. 871158). GWP acknowledges long-term support from CNES, the French space agency. LL acknowledges the financial contribution from the INAF grant 1.05.12.04.01. EP acknowledges support from CNES, the French national space agency and from ANR the French Agence Nationale de la Recherche, under grant ANR-22-CE31-0010. J.K. acknowledges the support by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education(2019R1A6A1A10073887) and the 2025 KAIST-U.S. Joint Research Collaboration Open Track Project for Early-Career Researchers, supported by the International Office at the Korea Advanced Institute of Science and Technology (KAIST). M.G. acknowledges support from the ERC Consolidator Grant BlackHoleWeather (101086804). MDP acknowledges financial support from PRIN-MUR grant 20228B938N “Mass and selection biases of galaxy clusters: a multi-probe approach” funded by the European Union Next generation EU, Mission 4 Component 1 CUP C53D2300092 0006. DE acknowledges support from the Swiss National Science Foundation (SNSF) through grant agreement #200021_212576. BJM acknowledges support from Science and Technology Facilities Council grants ST/V000454/1 and ST/Y002008/1.

Files

aa55719-25.pdf

Files (739.8 kB)

Name Size Download all
md5:2da6d74ced11713b6e08d7b64a22b178
739.8 kB Preview Download

Additional details

Related works

Is new version of
Discussion Paper: arXiv:2505.23005 (arXiv)

Funding

International Space Science Institute
565
National Aeronautics and Space Administration
80NSSC21K1571
European Union
20227RNLY3
National Institute for Astrophysics
1.05.01.86.10
National Institute for Astrophysics
1.05.23.06.17
European Union
AHEAD2020 871158
Centre National d'Études Spatiales
National Institute for Astrophysics
1.05.12.04.01
Agence Nationale de la Recherche
ANR-22-CE31-0010
National Research Foundation of Korea
2019R1A6A1A10073887
Korea Advanced Institute of Science and Technology
European Research Council
BlackHoleWeather 101086804
Ministero dell'università e della ricerca
PRIN-MUR 20228B938N
European Union
C53D2300092 0006
Swiss National Science Foundation
200021_212576
Science and Technology Facilities Council
ST/V000454/1
Science and Technology Facilities Council
ST/Y002008/1

Dates

Accepted
2025-06-10
Available
2025-08-11
Published online

Caltech Custom Metadata

Caltech groups
Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published