Abstract 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 …

We study the implications of Planck data for models of dark energy (DE) and modified gravity
(MG) beyond the standard cosmological constant scenario. We start with cases where the …

We present the current accounting of systematic effect uncertainties for the Low Frequency
Instrument (LFI) that are relevant to the 2015 release of the Planck cosmological results …

We make precise the heretofore ambiguous statement that anisotropic stress is a sign of a
modification of gravity. We show that in cosmological solutions of very general classes of …

Some of the dark matter in the Universe is made up of massive neutrinos. Their impact on
the formation of large scale structure can be used to determine their absolute mass scale …

We perform three-dimensional numerical relativity simulations of homogeneous and
inhomogeneous expanding spacetimes, with a view toward quantifying nonlinear effects …

We present a framework for general relativistic N-body simulations in the regime of weak
gravitational fields. In this approach, Einsteinʼs equations are expanded in terms of metric …

In this mini-review we discuss first why we should investigate cosmological models beyond
ΛCDM. We then show how to describe dark energy or modified gravity models in a fluid …

The effective anisotropic stress or gravitational slip η=-Φ/Ψ is a key variable in the
characterization of the physical origin of the dark energy, as it allows us to test for a …

In many generalized models of gravity, perfect fluids in cosmology give rise to gravitational
slip. Simultaneously, in very broad classes of such models, the propagation of gravitational …