1209.0520 (Zhigang Li et al.)

Anomalous anisotropic cross-correlations between WMAP CMB maps and SDSS galaxy distribution and implications on the dark flow scenario    [PDF]

Zhigang Li, Pengjie Zhang, Xuelei Chen

We search for the dark flow induced diffuse kinetic Sunyaev Zel'dovich (kSZ) effect through CMB-galaxy cross correlation. Such angular correlation is anisotropic, with a unique $cos(theta_DF)$ angular dependence and hence can be distinguished from other components. Here, $theta_DF$ is the angle between the opposite dark flow direction and the direction of the sky where the correlation is measured. We analyze the KIAS-VAGC galaxy catalog of SDSS-DR7 and the WMAP seven-year temperature maps, applying an unbiased optimal weighting scheme to eliminate any statistically isotropic components and to enhance the dark flow detection signal. Non-zero weighted cross correlations are detected at 3.5 sigma for the redshift bin z<0.1 and at 3 sigma for the bin 0.1 6000 km/s). We report this work as the first attempt to search for dark flow through weighted CMB-galaxy cross correlation and to draw the attention on the sources of the detected anomalous CMB-galaxy cross correlation.

View original: http://arxiv.org/abs/1209.0520