2016/04/30 by Jarah Evslin · 25 citations
Physics and Astronomy · #Anisotropy #Astrophysics #Baryon #Baryon acoustic oscillations #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Equation of state #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hubble's law #Lambda #Omega #Particle physics #Physics #Planck #Quantum mechanics #Redshift #astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2017/04/024
published in Journal of Cosmology and Astroparticle Physics 2017(04), 024 (Institute of Physics) · 25 pages, 19 pdf figures, v3: CMB acoustic scale measurement included
openalex publication_date 2017/04/13 · arxiv created 2017/05/01 · arxiv updated 2017/05/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/08
A 2.5-3σ discrepancy has been reported between the baryonic acoustic oscillation peak (BAO) in the Lyman α forest at z ∼ 2.34 and the best fit Planck ΛCDM cosmology. To isolate the origin of the tension, we consider unanchored BAO, in which the standard BAO ruler is not calibrated, eliminating any dependence on cosmology before redshift z ∼ 2.34. We consider BOSS BAO measurements at z ∼ 0.32, 0.57 and 2.34, using the full 2-dimensional constraints on the angular and line of sight BAO scale, as well as isotropic BAO measurements by 6dF and SDSS at z ∼ 0.106 and z ∼ 0.15. We find that the z >0.43 data alone is in 2.9σ of tension with ΛCDM with or without the Planck best fit values of the mass fraction Ω m and the BAO scale r d H 0 , indicating that the tension arises not from the ΛCDM parameters but from the dark energy evolution itself at 0.57< z <2.34. This conclusion is supported when the acoustic scale measured by the CMB is included, which further increases the tension and excludes a solution with a constant dark energy equation of state. Including the low z BAO data, which is itself consistent with ΛCDM, reduces the tension to just over 2σ, however in this case a CPL parametrization of the dark energy evolution yields only a modest improvement.