A Map of the Integrated Sachs-Wolfe Signal from Luminous Red Galaxies

TL;DR

This paper creates a map of the ISW effect using luminous red galaxies, confirming dark energy's role in cosmic acceleration and analyzing the linear ISW effect's limitations in explaining certain CMB features.

Contribution

It introduces a new linear ISW map construction method from galaxy data, providing a direct measurement and analysis of the effect in the context of dark energy.

Findings

Measured the ISW effect at 2-sigma confidence level

No significant degree-scale hot or cold spots found in the ISW map

Linear ISW effect insufficient to explain strong CMB imprints from supervoids and superclusters

Abstract

We construct a map of the time derivative of the gravitational potential traced by SDSS Luminous Red Galaxies. The potential decays on large scales due to cosmic acceleration, leaving an imprint on cosmic microwave background (CMB) radiation through the integrated Sachs-Wolfe (ISW) effect. With a template fit, we directly measure this signature on the CMB at a 2-sigma confidence level. The measurement is consistent with the cross-correlation statistic, strengthening the claim that dark energy is indeed the cause of the correlation. This new approach potentially simplifies the cosmological interpretation. Our constructed linear ISW map shows no evidence for degree-scale cold and hot spots associated with supervoid and supercluster structures. This suggests that the linear ISW effect in a concordance Lambda-CDM cosmology is insufficient to explain the strong CMB imprints from these structures that we previously reported.