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arXiv · 1205.2729

Gravitational softening as a smoothing operation

Joshua E. Barnes
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Abstract

In self-consistent N-body simulations of collisionless systems, gravitational interactions are modified on small scales to remove singularities and simplify the task of numerically integrating the equations of motion. This `gravitational softening' is sometimes presented as an ad-hoc departure from Newtonian gravity. However, softening can also be described as a smoothing operation applied to the mass distribution; the gravitational potential and the smoothed density obey Poisson's equation precisely. While `softening' and `smoothing' are mathematically equivalent descriptions, the latter has some advantages. For example, the smoothing description suggests a way to set up N-body initial conditions in almost perfect dynamical equilibrium.

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Joshua E. Barnes. 2012-08-24. Gravitational softening as a smoothing operation. https://doi.org/10.1111/j.1365-2966.2012.21462.x

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