Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern Hemisphere

Understand

The Integrated Sachs-Wolfe (ISW) effect probes the late-time expansion history of the universe, offering direct constraints on dark energy.

• Here we present our measurements of the ISW signal at redshifts of $\bar{z}=0.35$, $0.55$ and $0.68$, using the cross-correlation of the Planck CMB temperature map with $\sim0.5$ million Luminous Red Galaxies (LRGs) selected from the VST ATLAS survey.
• We then combine these with previous measurements based on WMAP and similar SDSS LRG samples, providing a total sample of $\sim2.1$ million LRGs covering $\sim12000$ deg$^2$ of sky.
• At $\bar{z}=0.35$ and $\bar{z}=0.55$ we detect the ISW signal at $1.2\sigma$ and $2.3\sigma$ (or $2.6\sigma$ combined), in agreement with the predictions of $\Lambda$CDM.