Study of baryon acoustic oscillations with SDSS DR12 data and measurement of ${\Omega }_{\text{DE}}(a)$

Abstract

We define Baryon Acoustic Oscillation (BAO) distances ${\hat{d}}_{\alpha }(z,z_c)$, ${\hat{d}}_z(z,z_c)$, and ${\hat{d}}_{/}(z,z_c)$ that do not depend on cosmological parameters. These BAO distances are measured as a function of redshift $z$ with the Sloan Digital Sky Survey (SDSS) data release DR12. From these BAO distances alone, or together with the correlation angle ${\theta }_{\text{MC}}$ of the Cosmic Microwave Background (CMB), we constrain the cosmological parameters in several scenarios. We find $4.3\sigma$ tension between the BAO plus ${\theta }_{\text{MC}}$ data and a cosmology with flat space and constant dark energy density ${\Omega }_{\text{DE}}(a)$. Releasing one and/or the other of these constraints obtains agreement with the data. We measure ${\Omega }_{\text{DE}}(a)$ as a function of $a$.

9 pages, 4 figures