The integrated Sachs–Wolfe effect in cosmologies with coupled dark matter and dark energy

• Published in: Monthly notices of the Royal Astronomical Society Vol. 388; no. 3; pp. 1403 - 1408
• Main Author: Schaefer, B M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 11.08.2008; Blackwell Science; Oxford University Press
• Subjects: Astronomy; Astrophysics; cosmic microwave background; Dark energy; Dark matter; Earth, ocean, space; Exact sciences and technology; large-scale structure of Universe; methods: analytical; methods: analytical; cosmic microwave background; large-scale structure of Universe; Coupling constants; Growth rate; Cosmic background radiation; Gravitational lensing; Poisson equation; Large-scale structure; Gravitational potential; Equations of state; Energy equation; Dark matter; Density perturbation; Violations; Analytical method; Cosmology; Density fluctuation; Models; Sachs Wolfe effect; Dark energy
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2008.13521.x

The subject of this paper is the derivation of the integrated Sachs–Wolfe (iSW) effect in cosmologies with coupled dark matter and dark energy fluids. These couplings influence the iSW effect in three ways: the Hubble function assumes a different scaling, the structure growth rate shows a different time evolution and, in addition, the Poisson equation, which relates the density perturbations to fluctuations in the gravitational potential, is changed, due to the violation of the scaling ρ∝a−3 of the matter density ρ with scalefactor a. Exemplarily, I derive the iSW spectra for a model in which dark matter decays into dark energy, investigate the influence of the dark matter decay rate and the dark energy equation of state on the iSW signal, and discuss the analogies for gravitational lensing. Quite generally, iSW measurements should reach similar accuracy in determining the dark energy equation of state parameter and the coupling constant.