Thierry Baertschiger

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We analyse with simple real-space statistics the Virgo consortium’s cosmological N-body simulations. Significant clustering rapidly develops well below the initial mean interparticle separation 〈Λi〉, where the gravitational force on a particle is dominated by that with its nearest neighbours. A power-law behaviour in the two point correlation function(More)
We apply a simple linearization, well known in solid state physics, to approximate the evolution at early times of cosmological N-body simulations of gravity. In the limit that the initial perturbations, applied to an infinite perfect lattice, are at wavelengths much greater than the lattice spacing l, the evolution is exactly that of a pressureless(More)
– Cosmological N-body simulations aim to calculate the non-linear gravitational growth of structures via particle dynamics. A crucial problem concerns the setting-up of the initial particle distribution, as standard theories of galaxy formation predict the properties of the initial continuous density field with small amplitude correlated Gaussian(More)
In this lecture we address three different but related aspects of the initial continuous fluctuation field in standard cosmological models. Firstly we discuss the properties of the so-called Harrison-Zeldovich like spectra. This power spectrum is a fundamental feature of all current standard cosmological models. In a simple classification of all stationary(More)
In two recent papers, a detailed study has been presented of the out-of-equilibrium dynamics of an infinite system of self-gravitating points initially located on a randomly perturbed lattice. In this paper, we extend the treatment of the early time phase during which strong nonlinear correlations first develop, prior to the onset of "self-similar" scaling(More)
– We present an analysis of different sets of gravitational N-body simulations, all describing the dynamics of discrete particles with a small initial velocity dispersion. They encompass very different initial particle configurations, different numerical algorithms for the computation of the force, with or without the space expansion of cosmological models.(More)
We study the statistics of the force felt by a particle in the class of a spatially correlated distribution of identical pointlike particles, interacting via a 1/r2 pair force (i.e., gravitational or Coulomb), and obtained by randomly perturbing an infinite perfect lattice. We specify the conditions under which the force on a particle is a well-defined(More)
We study the evolution under their self-gravity of particles evolving from infinite "shuffled lattice" initial conditions. We focus here specifically on the comparison between the evolution of such a system and that of "daughter" coarse-grained particle distributions. These are sparser (i.e., lower density) particle distributions, defined by a simple(More)
We study, using numerical simulations, the dynamical evolution of self-gravitating point particles in static Euclidean space, starting from a simple class of infinite "shuffled lattice" initial conditions. These are obtained by applying independently to each particle on an infinite perfect lattice a small random displacement, and are characterized by a(More)
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