Appraisal of the BAO equations
Year: 2017
Type: preprint
Abstract: The commonly used isotropic baryon acoustic oscillation (BAO) equation is an approximation derived from empirical and geometric arguments, and the equivalent anisotropic BAO equations were written down by analogy. Using fit-lines to CMB compatible solutions, {\Omega}_{m} and H_{0} values have been derived for BAO studies without recourse to those equations, and have been applied for their appraisal. The isotropic expression becomes problematic at precision levels of ~1 percent or better, and at high redshift values of z = / >1. Most revealing, the anisotropic equations, D_{M}(z)/D_{M,fid}(z)={\alpha}_{\perp}r_{d}/r_{d,fid}, and D_{H}(z)/D_{H,fid}(z)={\alpha}_{\parallel}r_{d}/r_{d,fid}, are invalid when {\alpha} ~ 1, since under that condition, D_{M}(z)/D_{M,fid}(z)=D_{H}(z)/D_{H,fid}(z)=r_{d}/r_{d,fid} ~ 1, and neither equation can be satisfied with anisotropic data. (The ratios are respectively, the angular distance, the inverse Hubble parameter, and the comoving acoustic horizon, each divided by its fiducial value). {\alpha} can be driven towards unity for any data set, e.g., by applying the derived {\Omega}_{m}, H_{0} pair as the core of a second iteration fiducial parameter-set. Thus, the anisotropic equations are untenable. Dissociated from the BAO equations, we have extracted weighted mean values of {\Omega}_{mw}=0.299+/-0.011 and H_{0w}=68.6+/-0.7 km s-1 Mpc-1 for eight uncorrelated BAO data sets.
Source: arXiv (Cornell University)
Author: J. S. Jayson
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2971402934