Breaking the baryon-dark matter degeneracy in a model-independent way through the Sunyaev-Zeldovich effect

Context. In cosmological fits, it is common to fix the baryon density ω b via the cosmic microwave background. We here constrain ω b by means of a model-independent interpolation of the acoustic parameter from correlated baryonic acoustic oscillations. Aims. The proposed technique is used to alleviate the degeneracy between baryonic and dark matter abundances. Methods. We propose a model-independent Bézier parametric interpolation and applied it to intermediate-redshift data. We first interpolated the observational Hubble data to extract cosmic bounds over the (reduced) Hubble constant h 0 and interpolated the angular diameter distances, D ( z ), of the galaxy clusters, inferred from the Sunyaev-Zeldovich effect, to constrain the spatial curvature, Ω k . Through the Hubble points and D ( z ) determined in this way, we interpolated uncorrelated data of baryonic acoustic oscillations bounding the baryon ω b and total matter ω m densities, reinforcing the constraints on h 0 and Ω k with the same technique. Finally, to remove the matter sector degeneracy, we obtained ω b by interpolating the acoustic parameter from correlated baryonic acoustic oscillations. Results. Monte Carlo Markov chain simulations agree at 1 σ confidence level with the flat ΛCDM model and are roughly suitable at 1 σ with its nonflat extension, while the Hubble constant appears in tension up to the 2 σ confidence levels. Conclusions. Our method excludes very small extensions of the standard cosmological model, and on the Hubble tension side, seems to match local constraints slightly.