Date Published:
June 1, 2017
Abstract:
We have used flux-transmission correlations in Lyα forests tomeasure the imprint of baryon acoustic oscillations (BAO). The studyuses spectra of 157 783 quasars in the redshift range 2.1 ≤ z ≤3.5 from the Sloan Digital Sky Survey (SDSS) data release 12 (DR12).Besides the statistical improvements on our previous studies using SDSSDR9 and DR11, we have implemented numerous improvements in the analysisprocedure, allowing us to construct a physical model of the correlationfunction and to investigate potential systematic errors in thedetermination of the BAO peak position. The Hubble distance,D
H = c/H(z), relative to the sound horizon is D
H(z= 2.33) /r
d = 9.07 ± 0.31. The best-determinedcombination of comoving angular-diameter distance, D
M, andthe Hubble distance is found to beD
H0.7D
M0.3 /r
d =13.94 ± 0.35. This value is 1.028 ± 0.026 times theprediction of the flat-ΛCDM model consistent with the cosmicmicrowave background (CMB) anisotropy spectrum. The errors includemarginalization over the effects of unidentified high-density absorptionsystems and fluctuations in ultraviolet ionizing radiation.Independently of the CMB measurements, the combination of our resultsand other BAO observations determine the open-ΛCDM densityparameters to be Ω
M = 0.296 ± 0.029,Ω
Λ = 0.699 ± 0.100 andΩ
k = -0.002 ± 0.119.
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