The BEHOMO project: Λ Lemaître-Tolman-Bondi N-body simulations

Abstract

Context. Our universe may feature large-scale inhomogeneities and anisotropies that cannot be explained by the standard model of cosmology, that is, the homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker metric, on which the Λ cold dark matter model is built, may not accurately describe observations. Currently, there is not a satisfactory understanding of the evolution of the large-scale structure on an inhomogeneous background. Aims. We have launched the cosmology beyond homogeneity and isotropy (BEHOMO) project to study the inhomogeneous Λ Lemaître-Tolman-Bondi model with the methods of numerical cosmology. Understanding the evolution of the large-scale structure is a necessary step in constraining inhomogeneous models with present and future observables and placing the standard model on more solid ground. Methods. We perform Newtonian N-body simulations, whose accuracy in describing the background evolution is checked against the general relativistic solution. The large-scale structure of the corresponding Λ cold dark matter simulation is also validated. Results. We obtain the first set of simulations of the Λ Lemaître-Tolman-Bondi model ever produced. The data products consist of 11 snapshots between redshift 0 and 3.7 for each of the 68 simulations that have been performed, together with halo catalogs and lens planes relative to 21 snapshots, between redshift 0 and 4.2, for a total of approximately 180 TB of data. Conclusions. We plan to study the growth of perturbations at the linear and nonlinear level, gravitational lensing, and cluster abundances and proprieties.