Physical Evidence for Dark Energy

TL;DR

This paper provides observational evidence for dark energy by detecting the late Integrated Sachs-Wolfe effect through cross-correlation of galaxy and CMB data, supporting the accelerated expansion of the universe.

Contribution

First detection of the ISW effect via galaxy-CMB cross-correlation, offering independent evidence for dark energy in a flat universe.

Findings

Significant achromatic positive correlation consistent with ISW effect

No large-scale anti-correlation indicating SZ effect is not dominant

Evidence of SZ effect at high redshifts

Abstract

We present measurements of the angular cross-correlation between luminous red galaxies from the Sloan Digital Sky Survey and the cosmic microwave background temperature maps from the Wilkinson Microwave Anisotropy Probe. We find a statistically significant achromatic positive correlation between these two data sets, which is consistent with the expected signal from the late Integrated Sachs-Wolfe (ISW) effect. We do not detect any anti-correlation on small angular scales as would be produced from a large Sunyaev-Zel'dovich (SZ) effect, although we do see evidence for some SZ effect for our highest redshift samples. Assuming a flat universe, our preliminary detection of the ISW effect provides independent physical evidence for the existence of dark energy.