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arXiv · 1201.2353

ORIGAMI: Delineating Halos using Phase-Space Folds

Bridget L. Falck·Mark C. Neyrinck·Alexander S. Szalay
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Abstract

We present the ORIGAMI method of identifying structures, particularly halos, in cosmological N-body simulations. Structure formation can be thought of as the folding of an initially flat three-dimensional manifold in six-dimensional phase space. ORIGAMI finds the outer folds that delineate these structures. Halo particles are identified as those that have undergone shell-crossing along 3 orthogonal axes, providing a dynamical definition of halo regions that is independent of density. ORIGAMI also identifies other morphological structures: particles that have undergone shell-crossing along 2, 1, or 0 orthogonal axes correspond to filaments, walls, and voids respectively. We compare this method to a standard Friends-of-Friends halo-finding algorithm and find that ORIGAMI halos are somewhat larger, more diffuse, and less spherical, though the global properties of ORIGAMI halos are in good agreement with other modern halo-finding algorithms.

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Bridget L. Falck, Mark C. Neyrinck, Alexander S. Szalay. 2012-01-11. ORIGAMI: Delineating Halos using Phase-Space Folds. https://doi.org/10.1088/0004-637x/754/2/126

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