GADGET is a freely available code for cosmological N-body/SPH simulations written by Volker Springel at the Max Planck Institute for Astrophysics. This article describes version 2 of GADGET (known as GADGET-2). Description GADGET computes gravitational forces with a hierarchical tree algorithm (optionally in combination with a particle-mesh scheme for long-range gravitational forces) and represents fluids by means of smoothed particle hydrodynamics (SPH). The code can be used for studies of isol… (More on Gadget)