Screening vs. gevolution: In chase of a perfect cosmological simulation code

Suppression of matter density growth at scales exceeding the cosmic screening length

“…The code [21,22] allows to calculate the power spectra of metric perturbations as well as that of the energy density contrast, and can easily be modified to study the behaviour of these quantities in the cosmic screening approach. Indeed, a comparative analysis was carried out in [23], and it was shown that despite the presence of second-order contributions to metric perturbations in gevolution, the power spectra of these potentials demonstrate very good agreement between the two schemes. Hence, the effect of second-order admixtures is small, as it should be, and the simpler form equations in the screening approach helps save almost 40% of CPU hours.…”

“…Now, to obtain P δ (k, z), we have modified gevolution [21,22] and replaced its default set of equations by that of the screening approach. This means that to single out the term δρ = ρ − ρ on the right hand side of the field equation (2.9) in [22], we have moved the additional Φ-dependent term in the perturbed energy-momentum tensor element δε = δT 0 0 = T 0 0 −T 0 0 (where T 0 0 is given by (3.7) of [22]) to the left hand side (see [23]). We have also dropped all second-order corrections and demanded that all particles are nonrelativistic.…”

Second-order dust perturbations of the non-flat FLRW model with the positive cosmological constant

“…Although the Einstein equations are very complicated and it is hard to discover new solutions, there is some progress in this field, e. g. [25] found a new class of interesting models. Another possibility is to study the evolution of the inhomogeneities within the numerical relativity [26,27,28,29] or by using the perturbative methods like the post-Newtonian formalism [30,31,32].…”

Second-order dust perturbations of the non-flat FLRW model with the positive cosmological constant

“…[25] found a new class of interesting models. Another possibility is to study the evolution of the inhomogeneities within the numerical relativity [26][27][28][29] or by using the perturbative methods like the post-Newtonian formalism [30][31][32].…”