A parallel implementation of a new fast algorithm for N-body simulations

TL;DR

This paper presents a parallel Fortran-90 implementation of a new fast, momentum-preserving Poisson solver for N-body simulations, applied to galaxy mergers to study their scaling relations.

Contribution

It introduces a parallelized, efficient N-body simulation code based on a recent algorithm, enabling detailed galaxy merger studies.

Findings

The Fundamental Plane is preserved in equal mass mergers.

The Fundamental Plane is not preserved in accretion scenarios.

Simulations do not reproduce Faber-Jackson and Kormendy relations.

Abstract

A new, momentum preserving fast Poisson solver for N-body systems sharing effective O(N) computational complexity, has been recently developed by Dehnen (2000, 2002). We have implemented the proposed algorithms in a Fortran-90 code, and parallelized it by a domain decomposition using the MPI routines. The code has been applied to intensive numerical investigations of galaxy mergers, in particular focusing on the possible origin of some of the observed scaling relations of elliptical galaxies. We found that the Fundamental Plane is preserved by an equal mass merging hierarchy, while it is not in a scenario where galaxies grow by accretion of smaller stellar systems. In addition, both the Faber-Jackson and Kormendy relations are not reproduced by our simulations.