COT1 - Dark Energy and Universe Acceleration |
Speaker_ |
Vasúth, Mátyás |
Co-autors |
Viktor Czinner |
Talk _ |
Perturbations of a cosmological constant dominated universe |
Abstract _ |
One of the proposed form of dark energy is the cosmological constant. We give the complete C^infty solution governing linear perturbations of a spatially flat Friedmann-Robertson-Walker model with a pressureless ideal fluid source and non-vanishing cosmological constant. Using the potential which belongs to the growing mode of the relative energy density fluctuations, we separated the Sachs–Wolfe and Integrated Sachs–Wolfe terms. It is found that the part of the Sachs–Wolfe term which becomes time dependent in the presence of a cosmological constant underwent a reversal approximately two billion years ago. Using the time dependence of the perturbation potentials we give the analytic expression for the argument of the ISW integral for an arbitrary initial power spectrum of the fluctuations. |