Probing dark energy models across scales: from linear to non-linear dynamics

The Universe has entered an accelerating expansion phase in the last few billion years of its evolution, a phenomenon that is caused by the mysterious entity known as dark energy. To understand the nature of dark energy, we must carefully investigate different viable candidates and observe how they affect the Universe at various stages. Then we may utilize data to select the best candidate. However, the consistent and accurate modeling of dark energy candidates has been largely neglected so far due to significant challenges, including the absence of proper non-linear treatments, the immense computational costs involved, and the limited availability of relevant data to date. To address the gaps, we have proposed the development of a novel framework called NEVO. This framework utilizes the state-of-the-art relativistic N-body code gevolution, along with the Boltzmann code hi_class. By incorporating the effective field theory of dark energy (EFT) formalism, we introduce a unified description for a large class of dark energy models. The EFT approach allows us to control the perturbations of these theories and accurately describe their dynamics across a wide range of scales using both N-body and Boltzmann codes. In this talk, I will present the key components of the NEVO project and demonstrate how our approach allows us to analyze a wide range of observables across multiple scales. This framework enables us to identify the observables that most effectively constrain various dark energy theories, while also revealing non-linear instabilities that impose additional constraints—even in the absence of direct cosmological data.