Cosmology from large-scale structure: Constraining ΛCDM with BOSS

We reanalyse the anisotropic galaxy clustering measurement from the Baryon Oscillation Spectroscopic Survey (BOSS), demonstrating that using the full shape information provides cosmological constraints that are comparable to other low-redshift probes. We find Ωm = 0:317+0:015 - 0:019, σ8 = 0:7100±049, and h = 0:704±0:024 for flat CDM cosmologies using uninformative priors on Ωch2, 100MC, ln 1010As, and ns, and a prior on Ωbh2 that is much wider than current constraints.We quantify the agreement between the Planck 2018
constraints from the cosmic microwave background and BOSS, finding the two data sets to be consistent within a flat CDM cosmology using the Bayes factor as well as the prior-insensitive suspiciousness statistic. Combining two low-redshift probes, we jointly analyse the clustering of BOSS galaxies with weak lensing measurements from the Kilo-Degree Survey (KV450). The combination of BOSS and KV450 improves the measurement by up to 45%, constraining σ8 = 0:702±0:029 and S 8 = σ8 pm=0:3 = 0:728±0:026. Over the full 5D parameter space, the odds in favour of a single cosmology describing galaxy clustering, lensing, and the cosmic microwave background are 7 ± 2. The suspiciousness statistic signals a 2:1 ± 0:3σ tension between the combined low-redshift probes and measurements from the cosmic microwave background.