The first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger. Indeed, during their propagation, gravitational waves pick... Show moreThe first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger. Indeed, during their propagation, gravitational waves pick up information about the spacetime as they are affected by its expansion and by the matter structures along the propagation path. The aim of this Thesis is to investigate which cosmological information is accessible from a gravitational wave detection, with a specific interest in the late time Universe. Show less
In this thesis we study the landscape of gravitational models which modify GR by introducing an additional scalar degree of freedom (d.o.f.) to source Cosmic Acceleration. In particular we... Show moreIn this thesis we study the landscape of gravitational models which modify GR by introducing an additional scalar degree of freedom (d.o.f.) to source Cosmic Acceleration. In particular we answer the question "What is the complete set of theoretical conditions a gravitational model must satisfy, in order to give a theoretically viable cosmology?". In order to study the theoretical stability of extended models of gravity we emplout the E ective Field Theory of Dark Energy and Modied Gravity (EFToDE/MG). This is a unifying framework which allows us to study the landscape of gravitational models in a broad and model independent way. This will allow us to answer the research question in a model independent way. Show less
