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Title: | Cosmological implications of baryon acoustic oscillation measurements |
Author: | Cuesta, Antonio J. Gontcho, Satya Gontcho A. Miralda Escudé, Jordi BOSS Collaboration |
Keywords: | Cosmologia Espectroscòpia de microones Cosmology Microwave spectroscopy |
Issue Date: | 14-Dec-2015 |
Publisher: | American Physical Society |
Abstract: | We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-α forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibrated physical scale of the sound horizon, the combination of BAO and SN data into an 'inverse distance ladder' yields a measurement of H0=67.3 ±1.1 km s-1 Mpc-1 , with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat Λ CDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy (Λ ), our BAO +SN +CMB combination yields matter density Ωm=0.301 ±0.008 and curvature Ωk=-0.003 ±0.003 . When we allow more general forms of evolving dark energy, the BAO +SN +CMB parameter constraints are always consistent with flat Λ CDM values at ≈1 σ . While the overall χ2 of model fits is satisfactory, the LyaF BAO measurements are in moderate (2 - 2.5 σ ) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, ∑mν<0.56 eV (95% confidence), improving to ∑mν<0.25 eV if we include the lensing signal in the Planck CMB power spectrum. In a flat Λ CDM model that allows extra relativistic species, our data combination yields Neff=3.43 ±0.26 ; while the LyaF BAO data prefer higher Neff when excluding galaxy BAO, the galaxy BAO alone favor Neff≈3 . When structure growth is extrapolated forward from the CMB to low redshift, standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates. |
Note: | Reproducció del document publicat a: http://dx.doi.org/10.1103/PhysRevD.92.123516 |
It is part of: | Physical Review D, 2015, vol. 92, num. 12, p. 123516-1-123516-38 |
URI: | http://hdl.handle.net/2445/99687 |
Related resource: | http://dx.doi.org/10.1103/PhysRevD.92.123516 |
ISSN: | 1550-7998 |
Appears in Collections: | Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB)) |
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