ISW measurements with photometric redshift surveys: 2MASS results and future prospects

TL;DR

This study assesses the potential to detect the Integrated Sachs-Wolfe effect using photometric redshift data from 2MASS and future surveys, finding current data inconclusive but outlining future prospects.

Contribution

It demonstrates that including photometric redshifts from 2MASS does not significantly improve ISW detection and evaluates future survey capabilities.

Findings

No significant ISW signal detected with 2MASS data.

Likelihood ratio of 1.5:1 favoring LambdaCDM over no correlation.

Future surveys may still face detection challenges, with >10% chance of non-detection.

Abstract

In a flat universe dominated by dark energy, the Integrated Sachs-Wolfe (ISW) effect can be detected as a large-angle cross-correlation between the CMB and a tracer of large scale structure. We investigate whether the inconclusive ISW signal derived from 2MASS galaxy maps can be improved upon by including photometric redshifts for the 2MASS galaxies. These redshifts are derived by matching the 2MASS data with optical catalogues generated from SuperCOSMOS scans of major photographic sky surveys. We find no significant ISW signal in this analysis; an ISW effect of the form expected in a LambdaCDM universe is only weakly preferred over no correlation, with a likelihood ratio of 1.5:1. We consider ISW detection prospects for future large scale structure surveys with fainter magnitude limits and greater survey depth; even with the best possible data, the ISW cross-correlation signal would be expected to evade detection in >~ 10% of cases.