2005/04/30 by M. Joyce, B. Marcos, A. Gabrielli +2 · 1 citation
Physics and Astronomy · #astro-ph #cond-mat.other
paper · pdf · doi:10.1103/physrevlett.95.011304
published as Phys.Rev.Lett. 95 (2005) 011304 · 4 pages, 2 figures, version with minor modifications, accepted for publication in Phys. Rev. Lett
arxiv created 2005/05/25 · arxiv updated 2009/12/01
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 self-gravitating fluid treated in the analagous (Lagrangian) linearization, with the Zeldovich approximation as a sub-class of asymptotic solutions. Our less restricted approximation allows one to trace the evolution of the discrete distribution until the time when particles approach one another (i.e. ``shell crossing''). We calculate modifications of the fluid evolution, explicitly dependent on l i.e. discreteness effects in the N body simulations. We note that these effects become increasingly important as the initial red-shift is increased at fixed l. The possible advantages of using a body centred cubic, rather than simple cubic, lattice are pointed out.