Dark Electromagnetism: exploring the interactions between Dark Energy and light, theory and signatures

The project consists of two parts. The first part of the project will involve the survey of the available models of Dark Energy, in particular those which employ a Dark energy quantum field. Once the interaction is defined and characterised, the next st ep is to study the models from a theoretical perspective, looking for the solutions of the background equations describing the coupled evolution of Dark Energy and light with the expansion of the Universe. Effort will be also devoted to theoretical model building specific to this project, either by first parametrising in the most general way the quantities needed in describing the Dark Energy-Electromagnetism coupling and then solving for the evolution, or by performing a scan in the parameter space of a ll the evolution histories of such Dark Energy component compatible with current data to extract those that can generate a magnetic field of appreciable strength. The second part of the project focusses on the multitude of cosmological (but not limited t o cosmological) signatures of the models. To assess the viability of each model and the range the unknown parameters describing it can span to not conflict with experiment, the perturbation equations in the general relativistic cosmological background wi ll be analysed, solved analytically or numerically. The effects which this novel set of correlations are going to deliver include: distortions and new features (such as parity violation) of the cosmic microwave background anisotropy and polarisation spec tra, Sachs-Wolfe and Integrated Sachs-Wolfe effects, distortions in the matter perturbations power spectrum, statistical correlations of distant objects polarisation angles, cosmological birefringence, time variation of fundamental coupling constants. Th is is expected to open an entirely new window for uncovering the properties of the Dark Energy component, and would allow us to study Dark Energy through large scale magnetic fields observations, and viceversa.