Ray tracing the integrated Sachs-Wolfe effect through the light cones of the Dark Energy Universe Simulation -- Full Universe Runs

TL;DR

This study uses large-volume N-body simulations and ray-tracing to generate full-sky ISW maps, assessing their potential to differentiate dark energy models through cross-correlations with matter and lensing data.

Contribution

It introduces a comprehensive simulation-based approach to model the late ISW effect without replica techniques, enabling detailed comparison of dark energy scenarios.

Findings

ISW-lensing correlations match Planck measurements

Future surveys could distinguish dark energy models

Non-linear Rees-Sciama effect provides additional dark sector insights

Abstract

The late integrated Sachs-Wolfe (ISW) effect correlates the Cosmic Microwave Background (CMB) temperature anisotropies with foreground cosmic large-scale structures. As the correlation depends crucially on the growth history in the era of dark energy, it is a key observational probe for constraining the cosmological model. Here we present a detailed study based on full-sky and deep light cones generated from very large volume numerical N-body simulations, which allow us to avoid the use of standard replica techniques, while capturing the entirety of the late ISW effect on the large scales. We post-process the light cones using an accurate ray-tracing method and construct full-sky maps of the ISW temperature anisotropy for three different dark energy models. We quantify in detail the extent to which the ISW effect can be used to discriminate between different dark energy scenarios when cross-correlated with the matter distribution or the CMB lensing potential. We also investigate the onset of non-linearities, the so-called Rees-Sciama effect which provides a complementary probe of the dark sector. We find the signal of the lensing-lensing and ISW-lensing correlation of the three dark energy models to be consistent with measurements from the Planck satellite. Future surveys of the large-scale structures may provide cross-correlation measurements that are sufficiently precise to distinguish the signal of these models. Our methodology is very general and can be applied to any dark energy or modified gravity scenario as long as the metric seen by photons can still be characterized by a Weyl potential.