PUB - Publikationen an der Universität Bielefeld

A crucial diagnostic of the Lambda CDM cosmological model is the integrated Sachs-Wolfe (ISW) effect of large-scale structure on the cosmic microwave background (CMB). The ISW imprint of superstructures of size similar to 100 h(-1)Mpc at redshift z similar to 0.5 has been detected with > 4 sigma significance, however it has been noted that the signal is much larger than expected. We revisit the calculation using linear theory predictions in Lambda CDM cosmology for the number density of superstructures and their radial density pro file, and take possible selection effects into account. While our expected signal is larger than previous estimates, it is still inconsistent by > 3 sigma with the observation. If the observed signal is indeed due to the ISW effect then huge, extremely underdense voids are far more common in the observed universe than predicted by Lambda CDM.