The 2-point angular correlation function $w(\theta )$ (2PACF), where $\theta$ is the angular separation between pairs of galaxies, provides the transversal baryon acoustic oscillation (BAO) signal almost model independently. In this paper we use 409 337 luminous red galaxies in the redshift range $z=[0.440,0.555]$ obtained from the tenth data release of the Sloan Digital Sky Survey (SDSS DR10) to estimate ${\theta }_{\mathrm{BAO}}(z)$ from the 2PACF at six redshift shells. Since noise and systematics can hide the BAO signature in the $w\text{−}\theta$ plane, we also discuss some criteria to localize the acoustic bump. We identify two sources of model dependence in the analysis, namely, the value of the acoustic scale from cosmic microwave background (CMB) measurements and the correction in the ${\theta }_{\mathrm{BAO}}(z)$ position due to projection effects. Constraints on the dark energy equation-of-state parameter $\mathrm{w}(z)$ from the ${\theta }_{\mathrm{BAO}}(z)$ diagram are derived, as well as from a joint analysis with current CMB measurements. We find that the standard $\mathrm{\Lambda }\mathrm{CDM}$ model as well as some of its extensions are in good agreement with these ${\theta }_{\mathrm{BAO}}(z)$ measurements.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

We investigate the large scale anomalies in the angular distribution of the cosmic microwave background radiation as measured by WMAP using several tests. These tests, based on the multipole vector expansion, measure correlations between the phases of the multipoles as expressed by the directions of the multipole vectors and their associated normal planes. We have computed the probability distribution functions for 46 such tests, for the multipoles l=2-5. We confirm earlier findings that point to a high level of alignment between l=2 (quadrupole) and l=3 (octopole), but with our tests we do not find significant planarity in the octopole. In addition, we have found other possible anomalies in the alignment between the octopole and the l=4 (hexadecupole) components, as well as in the planarity of l=4 and l=5. We introduce the notion of a total likelihood to estimate the relevance of the low-multipoles tests of non-gaussianity. We show that, as a result of these tests, the CMB maps which are most widely used for cosmological analysis lie within the ~ 10% of randomly generated maps with lowest likelihoods.Comment: References added, updated discussion on alignment with Ecliptic Plane. 12 Pages, 6 Figures. Results for additional maps, the normalized frequencies for the tests and a Mathematica Notebook that computes the tests can be found on http://fma.if.usp.br/~abramo/MVA.htm

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics