General relativistic cosmological N-body simulations. Part I. Time integration

Galaxy tracers in cosmological N-body simulations

Galaxies, and the large-scale structure that they trace, grew via gravitational instability from small amplitude Gaussian density fluctuations. This nonlinear process can be studied by means of N -body simulations. The main target of this approach is to evaluate various cosmological theories of structure formation. Unfortunately, the dynamical range of current cosmological simulations is inadeq...

Discreteness effects in cosmological N-body simulations

An estimate of the convergence radius of a simulated CDM halo is obtained under the assumption that the peak phase-space density in the system is set by discreteness effects that operate prior to relaxation. The predicted convergence radii are approximately a factor 2 larger than those estimated for numerical convergence studies. A toy model is used to study the formation of sheets of the cosmi...

N-body Code for Cosmological Simulations

We present a new high-resolution N -body algorithm for cosmological simulations. The algorithm employs a traditional particle-mesh technique on a cubic grid and successive multilevel relaxations on the finer meshes, introduced recursively in a fully adaptive manner in the regions where the density exceeds a predefined threshold. The mesh is generated to effectively match an arbitrary geometry o...

Time stepping N-body simulations

Leapfrog integration has been the method of choice in N-body simulations owing to its low computational cost for a symplectic integrator with second order accuracy. We introduce a new leapfrog integrator that allows for variable timesteps for each particle in large N-body simulations. Tests with single particles in fixed potentials show that it behaves as a symplectic integrator. We then examin...

Analysing Bound Structures in Cosmological N-body Simulations