Cosmology and fundamental physics with the Euclid satellite.

Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid's Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission.

Analog cosmology with two-fluid systems in a strong gradient magnetic field.

We propose an experiment combining fluid dynamics and strong magnetic field physics to simulate cosmological scenarios. Our proposed system consists of two immiscible, weakly magnetized fluids moved through a strong gradient magnetic field. The diamagnetic and paramagnetic forces thus generated amount to a time-dependent effective gravity, which allows us to precisely control the propagation speed of interface waves. Perturbations on the interface therefore experience a nonstationary effective metric. In what follows, we demonstrate that our proposed system is capable of simulating a variety of cosmological models. We then present a readily realizable experimental setup which will allow us to capture the essential dynamics of standard inflation, wherein interface perturbations experience a shrinking effective horizon and are shown to transition from oscillatory to frozen and squeezed regimes at horizon crossing.