Constraining Galaxy Cluster Triaxiality via Weak Lensing --- I. Preparation for the Rubin Data Beyond Leading Order
Year: 2026
Type: preprint
Abstract: The 3D mass distributions of galaxy clusters are generally triaxial, a geometry that is difficult to constrain from projected observations. In this work, we measure the projected halo shapes of clusters from weak lensing signatures using the Cluster Lensing Mass Modeling software, a tool developed by the Dark Energy Science Collaboration to analyze data from NSF-DOE Rubin Observatory's Legacy Survey of Space and Time (LSST). We measure ensemble halo ellipticity on the plane of the sky via axis-aligned stacking and multipole expansion of weak lensing signatures. We study a precursor dataset --- the redMaPPer cluster catalog, the metacalibration shape catalog, and the Directional Neighborhood Fitting photometric redshift catalog from the Dark Energy Survey Year 3 public data release. We select clusters that have a high centering probability (>90%) of the identified central galaxy, and use the satellite galaxy distribution to determine the major-axis orientation for stacking. We extend the analysis to the second order of ellipticity in monopole and quadrupole measurements. The projected ellipticity of the cluster sample is found to be $0.307^{+0.013}_{-0.014}$ (axis ratio $0.530^{+0.016}_{-0.015}$) with extra percent-level systematics introduced mainly by miscentering. The projected cluster ellipticity shows no statistically significant dependence on redshift or richness (mass proxy). We further verify the accuracy of the cluster shape measurement using mock catalogs. This analysis is applicable to datasets from wide-area cosmic surveys such as LSST, Euclid, and the Roman Space Telescope, where larger sample sizes will lead to tighter constraints on cluster shapes.
Source: arXiv (Cornell University)
Authors: Fu, Shenming, Srinivasan, Radhakrishnan, Shin, Tae-hyeon, Solomon, Rance, Jones, Deric, Avestruz, Camille, Zhang, Yuanyuan, Aguena, Michel, Combet, Céline, Englert, Anthony, Levine, Benjamin, Malz, Alex I., Payerne, Constantin, Ricci, Marina, von der Linden, Anja, Collaboration, the LSST Dark Energy Science
Institutions: SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, University of Michigan, National Institute for Astrophysics, Centre National de la Recherche Scientifique, Institut National de Physique Nucléaire et de Physique des Particules, Université Grenoble Alpes, Brown University, Stony Brook University, Space Telescope Science Institute, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CEA Paris-Saclay - Etablissement de Saclay, Institut de Recherche sur les Lois Fondamentales de l'Univers, Université Paris Cité, Laboratoire AstroParticule et Cosmologie
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Brown University, University of Pennsylvania, Ohio State University, University of Chicago, University of Portsmouth, National Energy Research Scientific Computing Center, University College London, University of Sussex, Deutsche Forschungsgemeinschaft, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Centre National de la Recherche Scientifique, Financiadora de Estudos e Projetos, Institut de Física d'Altes Energies, University of Illinois at Urbana-Champaign, Office of Science, Science and Technology Facilities Council, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Institut National de Physique Nucléaire et de Physique des Particules, Integrated Electronics Engineering Center, Binghamton University, Argonne National Laboratory, Fermilab, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory
Awards: G1079818582, G1141912172, G1143651532, G122673668, G1229526393, G1286236842, G1313983767, G1451874870, G1677143136, G1863003419, G2371548206, G262532246, G2638771445, G303061748, G3083819904, G3685081974, G3884951186, G419881185, G4235786860, G42916606, G4501827968, G4654690619, G4711507462, G495301720, G498139845, G5076365615, G5252970658, G5438923238, G5570207115, G618388848, G6447494072, G6652958823, G7354628648, G8382000481, G8726098666, G969889393
OpenAlex ID: W7160630348