Interacting dark sector within ETHOS : Cosmological constraints from SPT cluster abundance with DES and HST weak lensing data

Mazoun, A. and Bocquet, S. and Mohr, J. J. and Garny, M. and Rubira, H. and Klein, M. and Bleem, L. E. and Grandis, S. and Schrabback, T. and Aguena, M. and Allam, S. and Allen, S. W. and Alves, O. and Andrade-Oliveira, F. and Brooks, D. and Carnero Rosell, A. and Carrasco Kind, M. and Carretero, J. and Costanzi, M. and da Costa, L. N. and Davis, T. M. and Desai, S. and De Vicente, J. and Diehl, H. T. and Dodelson, S. and Doel, P. and Everett, S. and Flaugher, B. and Frieman, J. and García-Bellido, J. and Gassis, R. and Giannini, G. and Grün, D. and Gutierrez, G. and Hinton, S. R. and Hollowood, D. L. and James, D. J. and Kuehn, K. and Lahav, O. and Lee, S. and Lima, M. and Mahler, G. and Marshall, J. L. and Miquel, R. and Myles, J. and Ogando, R. L. C. and Pereira, M. E. S. and Pieres, A. and Plazas Malagón, A. A. and Porredon, A. and Reichardt, C. L. and Romer, A. K. and Samuroff, S. and Sanchez, E. and Sanchez Cid, D. and Sevilla-Noarbe, I. and Schubnell, M. and Smith, M. and Suchyta, E. and Swanson, M. E. C. and Tamošiūnas, A. and Tarle, G. and Tucker, D. L. and Vikram, V. and Weaverdyck, N. and Weller, J. and Wiseman, P. (2025) Interacting dark sector within ETHOS : Cosmological constraints from SPT cluster abundance with DES and HST weak lensing data. Physical Review D, 111 (8): 083543. ISSN 2470-0010

Abstract

We use galaxy cluster abundance measurements from the South Pole Telescope enhanced by multicomponent matched filter confirmation and complemented with mass information obtained using weak-lensing data from Dark Energy Survey Year 3 (DES Y3) and targeted Hubble Space Telescope observations for probing deviations from the cold dark matter paradigm. Concretely, we consider a class of dark sector models featuring interactions between dark matter (DM) and a dark radiation (DR) component within the framework of the effective theory of structure formation (ETHOS). We focus on scenarios that lead to power suppression over a wide range of scales, and thus can be tested with data sensitive to large scales, as realized, for example, for DM–DR interactions following from an unbroken non-Abelian SU(N) gauge theory (interaction rate with power-law index n=0 within the ETHOS parametrization). Cluster abundance measurements are mostly sensitive to the amount of DR interacting with DM, parametrized by the ratio of DR temperature to the cosmic microwave background (CMB) temperature, ξDR=TDR/TCMB. We find an upper limit ξDR<17% at 95% credibility. When the cluster data are combined with Planck 2018 CMB data along with baryon acoustic oscillation (BAO) measurements we find ξDR<10%, corresponding to a limit on the abundance of interacting DR that is around 3 times tighter than that from CMB + BAO data alone. We also discuss the complementarity of weak lensing informed cluster abundance studies with probes sensitive to smaller scales, explore the impact on our analysis of massive neutrinos, and comment on a slight preference for the presence of a nonzero interacting DR abundance, which enables a physical solution to the S8 tension.