Correlación en simulaciones cosmológicas

We present a method to implement relativistic corrections to the evolution of dark matter structures in Newtonian simulations of a ΛCDM universe via the initial conditions. We take the nonlinear correspondence between the Lagrangian (Newtonian) evolution of dark matter inhomo geneities and the synchronous-comoving (relativistic) matter density description, and use it to promote the relativistic constraint as the initial condition for numerical simulations of structure formation. In this case, the incorporation of Primordial non-Gaussianity (PNG) contributions as initial conditions is straightforward. We implement the relativistic, fNL and gNL contributions as initial conditions for the L-PICOLA code, and compute the power spectrum and bispectrum of the evolved matter field. We focus specifically on the case of largest values of non-Gaussianity allowed at 1 − σ by Planck observations (fNL = −4.2 and gNL = −7000). As a checkup, we show consistency with the one-loop perturbative prescription and with a fully relativistic simulation (GRAMSES) on the adequate scales. Our results confirm that both relativistic and PNG features are most prominent at very large scales and for squeezed triangulations. We discuss future prospects to probe these two contributions in the bispectrum of the matter density distribution. The expected result was obtained where the greatest difference was found in the bispectrum, since the 3-point correlation function mostly detects deviations from the Gaussian distribution. This difference was greater at the maximum scale that could be reached, which was at k = 10−2h/Mpc. For the case where PNG is included with previously mentioned parameters of fNL and gNL, it was 4% in the difference power spectrum with respect to the Gaussian simulations and 10% in the bis pectrum with a squeezed triagulation. In the case of PNG and relativistic contributions, the difference was 6% in the power spectrum and 15% in the bispectrum. In the reduced bispectrum, it was denoted that a local triangulation (squeezed type) there is a greater difference with respect to the Gaussian simulation. There was also agreement with simulations where the initial conditions are Newtonian and the gravitational evolu- tion is relativistic. These results have been published [2].