Letter to the Editor

Matter power spectrum reconstruction with KiDS-Legacy: Improved internal ΛCDM consistency and preference for strong baryonic feedback

¹ Lorentz Institute for Theoretical Physics, Leiden University, PO Box 9506 NL-2300 RA Leiden, The Netherlands
² Leiden Observatory, Leiden University, PO Box 9513 NL-2300 RA Leiden, The Netherlands
³ Universität Bonn, Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
⁴ Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing, 44780 Bochum, Germany
⁵ School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, NE1 7RU Newcastle-upon-Tyne, UK
⁶ Center for Theoretical Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
⁷ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁸ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁹ Zentrum für Astronomie, Universitatät Heidelberg, Philosophenweg 12, D-69120 Heidelberg, Germany
¹⁰ Institute for Theoretical Physics, Philosophenweg 16, D-69120 Heidelberg, Germany
¹¹ Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Universitá di Bologna, Via Piero Gobetti 93/2, I-40129 Bologna, Italy
¹² Istituto Nazionale di Astrofisica (INAF) – Osservatorio di Astrofisica e Scienza dello Spazio (OAS), Via Piero Gobetti 93/3, I-40129 Bologna, Italy
¹³ Istituto Nazionale di Fisica Nucleare (INFN) – Sezione di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna, Italy
¹⁴ INAF – Osservatorio Astronomico di Padova, Via dell’Osservatorio 5, 35122 Padova, Italy
¹⁵ Institute for Computational Cosmology, Ogden Centre for Fundament Physics – West, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹⁶ Centre for Extragalactic Astronomy, Ogden Centre for Fundament Physics – West, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK

^⋆ Corresponding authors: broxterman@strw.leidenuniv.nl, psimon@astro.uni-bonn.de

Received: 10 September 2025
Accepted: 8 October 2025

Abstract

Direct measurements of the matter power spectrum, P_m(k, z), provide a powerful tool for investigating the observed tensions between models of structure growth, while also testing the internal consistency of cosmological probes. We analysed the cosmic shear data from the final data release of the Kilo-Degree Survey (KiDS), and present a deprojected P_m(k, z), measured in up to three redshift bins. Compared to analyses using previous KiDS releases, we find improved internal consistency in the z ≲ 0.7 regime. At large scales, k ≲ 0.1 h Mpc⁻¹, our power spectrum reconstruction aligns with ΛCDM predictions with a density fluctuation amplitude σ₈ = 0.81. Furthermore, at small scales, k = 3–20 h Mpc⁻¹, the average matter power spectrum is suppressed by 30%±10% (stat.) ± 4% (sys.) with 2.8σ significance relative to a dark matter-only model, consistent with expectations of strong baryonic feedback.