Density fluctuation parameters and associated 3D power spectra for the CHEX-MATE and X-COP cluster samples for various regions of interest. Left: Joint posterior distributions of standard deviation, σ_δ, injection scale, ℓ_inj, and spectral index, α, of density fluctuation power spectrum parameters, estimated on the cleaned CHEX-MATE sample and with the X-COP parameters in the 0.1–0.25 and 0.25–0.5 R₅₀₀ rings, as computed in Dupourqué et al. (2023). The dashed black line represents the expected 11/3 index from Kolmogorov theory. Right: Associated 3D power spectra as defined from Eq. (1). The dashed slope indicates the expected slope from Kolmogorov. The scales are in units of R₅₀₀.