Alleviating the Hubble tension with the Λωs CDM model

We formulate a novel extension of the [Formula: see text]CDM model, named [Formula: see text]CDM, in which we consider an additional term at early times in order to alleviate the Hubble tension. This additional component, referred to as matter with pressure, indicates a barotropic fluid that is subdominant to dust and radiation as the Universe expands, thereby recovering the [Formula: see text]CDM paradigm at late times. We constrain the [Formula: see text]CDM cosmology by performing a Markov Chain Monte Carlo analysis with Planck 2018 CMB, DESI DR2, and Pantheon+SH0ES data. The results suggest that the barotropic factor and the normalized density of the new fluid are given, respectively, by [Formula: see text] and [Formula: see text]. With these two additional parameters, the Hubble constant is increased to [Formula: see text] km/s/Mpc, alleviating de facto the Hubble tension.