Propagation of sound waves in the early Universe imprinted characteristic density fluctuations known as baryon acoustic oscillation (BAO). Galaxies preferentially form in higher-density regions, so BAO can be measured using galaxy redshift surveys. Alam et al. report the final cosmological parameters from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) both independently of other datasets and in combination with alternative cosmological techniques. The authors found strong support for standard cosmology with cold dark matter, a flat Universe, and dark energy described by a cosmological constant. The only notable inconsistency was the well-known tension in measurements of the Hubble constant, which persists in the new data.
Phys. Rev. D 103, 083533 (2021).