Baryon acoustic oscillations (BAO) involve measuring the spatial distribution of galaxies to determine the growth rate of cosmic structures. We derive constraints on cosmological parameters from 17 uncorrelated BAO measurements that were collected from 333 published data points in the effective redshift range 0.106 ≤ z ≤ 2.36. We test the correlation of the subset using a random covariance matrix. The Λ cold dark matter (ΛCDM) model fit yields the cosmological parameters Ω_m = 0.261 ± 0.028 and Ω_Λ = 0.733 ± 0.021. Combining the BAO data with the Cosmic Chronometers data, the Pantheon type Ia supernova, and the Hubble diagram of gamma-ray bursts and quasars, the Hubble constant yields 69.85 ± 1.27 km s⁻¹Mpc⁻¹and the sound horizon distance gives 146.1 ± 2.15 Mpc. Beyond the ΛCDM model we test Ω_kCDM andwCDM. The spatial curvature is Ω_k = −0.076 ± 0.012 and the dark energy equation of states isw = −0.989 ± 0.049. We perform the Akaike information criteria test to compare the three models, and see that ΛCDM scores best.

We investigated a possible interaction between cold dark matter and dark energy, corresponding to a well-known interacting dark energy model discussed in the literature within the context of resolving the Hubble tension. We put constraints on it in a novel way, by creating new likelihoods with an analytical marginalization over the Hubble parameterH₀, the sound horizonr_d, and the supernova absolute magnitudeM_B. Our aim is to investigate the impacts on the coupling parameter of the interacting model,ξ, and the equation of state of dark energywand the matter density parameter Ω_m, 0. The late-time cosmological probes used in our analysis include the PantheonPlus (calibrated and uncalibrated), cosmic chronometers, and baryon acoustic oscillation samples and the Pantheon for comparison. Through various combinations of these datasets, we demonstrate hints of an up to 2σdeviation from the standard Λ cold dark matter model.

Here we generalize ideas of unified dark matter–dark energy in the context of two measure theories and of dynamical space time theories. In two measu

A unification of dark matter and dark energy based on a dynamical spacetime theory is suggested. By introducing a dynamical spacetime vector field ${\chi }_{\mu }$ as a Lagrange multiplier, conservation of an energy momentum tensor $T_{(\chi )}^{\mu \nu }$ is implemented. This Lagrangian generalizes the “unified dark energy and dark matter from a scalar field different from quintessence” [ Phys. Rev. D 81, 043520 (2010)], which did not consider a Lagrangian formulation. This generalization allows the solutions which were found previously, but in addition to that also nonsingular bouncing solutions that rapidly approach to the $\mathrm{\Lambda }\mathrm{CDM}$ model. The dynamical time vector field exactly coincides with the cosmic time for the a $\mathrm{\Lambda }\mathrm{CDM}$ solution and suffers a slight shift (advances slower) with respect to the cosmic time in the region close to the bounce for the bouncing nonsingular solutions. In addition, we introduce some exponential potential which could enter into the $T_{(\chi )}^{\mu \nu }$ stress energy tensor or be coupled directly to the measure $\sqrt{-g}$, giving a possible interaction between dark energy and dark matter, and could explain the coincidence problem.