Stochastic contribution to the growth factor in the ΛCDM model

We study the effect of noise on the evolution of the growth factor of density perturbations in the context of the ΛCDM model. Stochasticity is introduced as a Wiener process amplified by an intensity parameter α. By comparing the evolution of deterministic and stochastic cases for different values of α we estimate the intensity level necessary to make noise relevant for cosmological tests based on large-scale structure data. Our results indicate that the presence of random forces underlying the fluid description can lead to significant deviations from the nonstochastic solution at late times for α≥10-3.