2014/09/30 by Alan Heavens, Raul Jimenez, Raúl Jiménez +1 · 90 citations
Physics and Astronomy · #Astrophysics #Baryon acoustic oscillations #Cold dark matter #Cosmic distance ladder #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hubble's law #Metric expansion of space #Physics #Planck length #Quantum #Quantum gravity #Quantum mechanics #Radio Astronomy Observations and Technology #Redshift #Theoretical physics #Universe #astro-ph.CO
paper · pdf · doi:10.1103/physrevlett.113.241302
published in Physical Review Letters 113(24), 241302 (American Physical Society) · Accepted for publication in PRL. 5 pages, 4 figures
arxiv created 2014/11/18 · openalex publication_date 2014/12/11 · arxiv updated 2014/12/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We measure the length of the baryon acoustic oscillation (BAO) feature, and the expansion rate of the recent Universe, from low-redshift data only, almost model independently. We make only the following minimal assumptions: homogeneity and isotropy, a metric theory of gravity, a smooth expansion history, and the existence of standard candles (supernovæ) and a standard BAO ruler. The rest is determined by the data, which are compilations of recent BAO and type IA supernova results. Making only these assumptions, we find for the first time that the standard ruler has a length of 103.9±2.3h⁻¹ Mpc. The value is a measurement, in contrast to the model-dependent theoretical prediction determined with model parameters set by Planck data (99.3±2.1h⁻¹ Mpc). The latter assumes the cold dark matter model with a cosmological constant, and that the ruler is the sound horizon at radiation drag. Adding passive galaxies as standard clocks or a local Hubble constant measurement allows the absolute BAO scale to be determined (142.8±3.7 Mpc), and in the former case the additional information makes the BAO length determination more precise (101.9±1.9h⁻¹ Mpc). The inverse curvature radius of the Universe is weakly constrained and consistent with zero, independently of the gravity model, provided it is metric. We find the effective number of relativistic species to be N(eff)=3.53±0.32, independent of late-time dark energy or gravity physics.