We investigate the observational constraints on an interacting vacuum energy scenario with two different neutrino schemes (with and without a sterile neutrino) using the most recent data from cosmic microwave background (CMB) temperature and polarization anisotropy, baryon acoustic oscillations (BAO), type Ia supernovae from JLA sample and structure growth inferred from cluster counts. We find that inclusion of the galaxy clusters data with the minimal data combination $\mathrm{CMB}+\mathrm{BAO}+\mathrm{JLA}$ suggests an interaction in the dark sector, implying the decay of dark matter particles into dark energy, since the constraints obtained by including the galaxy clusters data yield a non-null and negative coupling parameter between the dark components at 99% confidence level. We deduce that the current tensions on the parameters $H_0$ and ${\sigma }_8$ can be alleviated within the framework of the interacting as well as noninteracting vacuum energy models with sterile neutrinos.

Within the Lambda cold dark matter (ΛCDM) model, measurements from recent cosmic microwave background (CMB) and weak lensing (WL) surveys have uncovered a ∼3σ disagreement in the inferred value of the parameter |$S_8 \equiv \sigma _8\sqrt{\Omega _\mathrm{ m}/0.3}$|⁠, quantifying the amplitude of late-time matter fluctuations. Before questioning whether the S₈ discrepancy calls for new physics, it is important to assess the view of measurements other than CMB and WL ones on the discrepancy. Here, we examine the role of measurements of the growth rate f(z) in arbitrating the S₈ discrepancy, considering measurements of fσ₈(z) from redshift-space distortions (RSDs). Our baseline analysis combines RSD measurements with geometrical measurements from baryon acoustic oscillations (BAO) and Type Ia Supernovae (SNeIa), given the key role of the latter in constraining Ω_m. From this combination and within the ΛCDM model, we find |$S_8 = 0.762^{+0.030}_{-0.025}$|⁠, and quantify the agreement between RSD + BAO + SNeIa and Planck to be at the 2.2σ level: the mild disagreement is therefore compatible with a statistical fluctuation. We discuss combinations of RSD measurements with other data sets, including the E_G statistic. This combination increases the discrepancy with Planck, but we deem it significantly less robust. Our earlier results are stable against an extension where we allow the dark energy equation of state w to vary. We conclude that, from the point of view of combined growth rate and geometrical measurements, there are hints, but no strong evidence yet, for the Planck ΛCDM cosmology overpredicting the amplitude of matter fluctuations at redshifts z ≲ 1. From this perspective, it might therefore still be premature to claim the need for new physics from the S₈ discrepancy.

The well-known tensions on the cosmological parameters [equation] and [equation] within the [equation]CDM cosmology shown by the Planck-CMB and LSS data are possibly due to the systematics in the...

We investigate the implications of the baryon acoustic oscillations measurement released by the Dark Energy Spectroscopic Instrument for interacting dark energy (IDE) models characterized by an energy-momentum flow from dark matter to dark energy. By combining Planck-2018 and Dark Energy Spectroscopic Instrument data, we observe a preference for interactions, leading to a nonvanishing interaction rate ξ = − 0.3 2 − 0.14 + 0.18 , which results in a present-day expansion rate H 0 = 70.8 − 1.7 + 1.4 km / s / Mpc , reducing the tension with the value provided by the SH0ES Collaboration to less than ∼ 1.3 σ . The preference for interactions remains robust when including measurements of the expansion rate H ( z ) obtained from the relative ages of massive, early-time, and passively evolving galaxies, as well as when considering distance moduli measurements from Type Ia supernovae sourced from the Pantheon-plus catalog using the SH0ES Cepheid host distances as calibrators. Overall, the IDE framework provides an equally good, or better, explanation of both high- and low-redshift observations compared to the lambda cold dark matter model, while also yielding higher H 0 values that align more closely with the local distance ladder estimates. However, a limitation of the IDE model is that it predicts lower Ω m and higher σ 8 values, which may not be fully consistent with large-scale structure data at the level. Published by the American Physical Society 2024