HOP: A New group finding algorithm for N body simulations
Dec, 199718 pages
Published in:
- Astrophys.J. 498 (1998) 137-142
e-Print:
- astro-ph/9712200 [astro-ph]
DOI:
Report number:
- IASSNS-AST-97-33
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Abstract: (arXiv)
We describe a new method (HOP) for identifying groups of particles in N-body simulations. Having assigned to every particle an estimate of its local density, we associate each particle with the densest of the N_hop particles nearest to it. Repeating this process allows us to trace a path, within the particle set itself, from each particle in the direction of increasing density. The path ends when it reaches a particle that is its own densest neighbor: all particles reaching the same such particle are identified as a group. Combined with an adaptive smoothing kernel for finding the densities, this method is spatially adaptive, coordinate-free, and numerically straight-forward. One can proceed to process the output by truncating groups at a particular density contour and combining groups that share a (possibly different) density contour. While the resulting algorithm has several user-chosen parameters, we show that the results are insensitive to most of these, the exception being the outer density cutoff of the groups.References(14)
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