The integrated Sachs-Wolfe effect from the cross-correlation of CMB with LSS tracers

The ISW effect consists of small secondary fluctuations in the CMB which are produced as photons pass through time evolving gravitational potentials, as happens at late times, when the Universe is undergoing a transition to a curvature - or dark energy - dominated phase. The ISW is observed through the cross-correlation of CMB with LSS tracers. In this work we aim to demonstrate the importance of ISW when trying to constrain cosmological parameters by comparing the forecasted errors on parameters, obtained through Fisher analysis for two cases: when we include the CMB x LSS-tracers cross-corelation, which is mostly attributed to ISW on large scales, and when we do not. We performed this test on four different cosmologies and we found that not including the cross-correlation increases the forecasted error for all considered cosmologies.