The stacked ISW signal of rare superstructures in \Lambda CDM
  A detection of the stacked integrated Sachs-Wolfe (ISW) signal in the CMB of
rare superstructures identified in the SDSS Luminous Red Galaxy catalogue has
been reported at very high statistical significance. The magnitude of the
observed signal has previously been argued to be more than 3 standard
deviations larger than the theoretical \Lambda CDM expectation. However, this
calculation was made in the linear approximation, and relied on assumptions
that may potentially have caused the \Lambda CDM expectation to be
underestimated. Here we update the theoretical model calculation and compare it
with an analysis of ISW maps obtained from N-body simulations of a \Lambda CDM
universe. The differences between model predictions and the map analyses are
found to be small and cannot explain the discrepancy with observation, which
remains at >3 s.d. significance. We discuss the cosmological significance of
this anomaly and speculate on the potential of alternative models to explain
it.
