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

Abstract

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 $cos(thet{a}_{D}F)$ angular dependence and hence can be distinguished from other components. Here, $thet{a}_{D}F$ 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<z<0.2, implying the existence of statistically anisotropic components in CMB. However, further analysis does not support the dark flow explanation. The observed directional dependence deviates from the $\propto cos(thet{a}_{D}F)$ relation expected, and hence can not be explained by the presence of a single dark flow, and if the observed cross correlation is generated by the dark flow induced kSZ effect, the velocity would be too high (> 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.

8 pages, 8 figures, ApJ accepted

References in corpus (9)

• Correlation of CMB with large-scale structure: I. ISW Tomography and Cosmological Implications
• A full sky, low foreground, high resolution CMB map from WMAP
• Combined analysis of the integrated Sachs-Wolfe effect and cosmological implications
• Detection of the ISW and SZ effects from the CMB-Galaxy correlation
• Correlation of CMB with large-scale structure: II. Weak lensing
• A high redshift detection of the integrated Sachs-Wolfe effect
• Cross-correlation of WMAP 3rd year and the SDSS DR4 galaxy survey: new evidence for Dark Energy
• Error analysis in cross-correlation of sky maps: application to the ISW detection
• A reassessment of the evidence of the Integrated Sachs-Wolfe effect through the WMAP-NVSS correlation

Cited by in corpus (4)

• First measurement of the bulk flow of nearby galaxies using the cosmic microwave background
• Analyzing the cosmic variance limit of remote dipole measurements of the cosmic microwave background using the large-scale kinetic Sunyaev Zel'dovich effect
• On the Statistical Significance of the Bulk Flow Measured by the PLANCK Satellite
• Testing eternal inflation with the kinetic Sunyaev Zel'dovich effect