Integrated Sachs-Wolfe measurements with photometric redshift surveys: 2MASS results and future prospects

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 cosmic microwave background and a tracer of large-scale structure. We investigate whether the inconclusive ISW signal derived from Two-Micron All-Sky Survey (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 Λ cold dark matter 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 per cent of cases.