Cross-correlating WMAP5 with 1.5 million LRGs: a new test for the ISW effect

Understand

We present the cross-correlation of the density map of LRGs and the temperature fluctuation in the CMB as measured by the WMAP5 observations.

• The LRG samples were extracted from imaging data of the SDSS based on two previous spectroscopic redshift surveys, the SDSS-LRG and the 2SLAQ surveys at average redshifts z~0.35 and z~0.55.
• In addition we have added a higher-redshift photometric LRG sample based on the selection of the AAOmega LRG redshift survey at z~0.7.
• The total LRG sample thus comprises 1.5 million galaxies, sampling a redshift range of 0.2 < z < 0.9 over ~7600 square degrees of the sky, probing a total cosmic volume of ~5.5 h^{-3} Gpc^3.