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Researchers have developed EFT-RAMSES, a new computational code that simulates dark energy and modified gravity models using the effective field theory framework. The code consolidates multiple theoretical models into a single "master" equation, eliminating the need for separate model-specific solvers, and has been validated through high-resolution N-body simulations showing excellent agreement with existing codes and linear theory predictions. This tool enables researchers to simulate non-linear cosmic structure formation across diverse dark energy scenarios within a unified computational framework.
Why it matters
This code provides cosmologists with a versatile, efficient tool to test alternatives to the standard cosmological constant model as high-precision data from next-generation surveys becomes available. By unifying multiple theoretical approaches in one simulation pipeline, it accelerates research into the physical nature of cosmic acceleration and helps prepare theoretical predictions for upcoming Stage-IV cosmological observations.
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⚠️ Preprint – Noch nicht peer-reviewed
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Abstract: While the standard $Lambda$CDM paradigm is in excellent agreement with most current cosmological observations, theoretical challenges surrounding the cosmological constant ($Lambda$) have strongly motivated the exploration of dynamical dark energy (DE) and modified gravity (MG) models. Investigating the physical nature of the cosmic acceleration requires N-body simulations to probe the non-linear growth of cosmic structure and prepare for the high-precision data from Stage-IV surveys. In this paper, we present EFT-RAMSES, a comprehensive extension of the ECOSMOG cosmological simulation code designed to explore non-linear structure formation in DE and MG scenarios. We embed the effective field theory of dark energy (EFTofDE) framework into this new numerical pipeline, utilising the $alpha$-basis parameterisation to provide a versatile, model-agnostic, computational engine. By consolidating diverse scalar and vector-tensor theories—including the normal and self-accelerating Dvali-Gabadadze-Porrati (DGP) models, cubic Galileons (cubic scalar Galileon (csG), cubic vector Galileon (cvG) and generalised cubic covariant Galileon (GCCG)), and generic effective field theory (EFT) parameterisation—into a single “master” Vainshtein equation, this pipeline bypasses the need for model-specific solvers and easily specialises to any particular model. As validations, we perform high-resolution N-body simulations for the normal-branch DGP (nDGP), csG, GCCG, and EFT models, comparing the resulting matter power spectra against dependent and independent codes such as legacy ECOSMOG and HiCOLA, as well as linear theory, and find excellent agreement. EFT-RAMSES provides a robust and versatile computational tool for precision cosmological tests of DE and MG using upcoming cosmological surveys. The code is available for download from the GitHub EFT-RAMSES repository.
Source: EFT-Ramses: a code to simulate the effective field theory of dark energy