Ignacy Sawicki

TL;DR: In this paper, the authors study a class of metric-variation models that accelerates the expansion without a cosmological constant and satisfies both cosmologically and solar-system tests in the small-field limit of the parameter space.

TL;DR: Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program as discussed by the authors, which will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shift of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky.

TL;DR: It is shown that the detection of an electromagnetic counterpart to the gravitational-wave signal from the merger of two neutron stars allows for stringent constraints on general scalar-tensor and vector-Tensor theories, while allowing for an independent bound on the graviton mass in bimetric theories of gravity.

TL;DR: In this paper, the authors introduce a large class of scalar-tensor models with interactions containing the second derivatives of the scalar field but not leading to additional degrees of freedom.

TL;DR: In this paper, the evolution of linear cosmological perturbations in f(R) models of accelerated expansion in the physical frame where the gravitational dynamics are fourth order and the matter is minimally coupled is studied.