2014/10/31 by Bridget Falck, Mark C. Neyrinck · 47 citations
Environmental Science · Physics and Astronomy · #Astrophysics #Bounded function #Dark matter #Galaxies: Formation, Evolution, Phenomena #Geometry #Mathematical analysis #Percolation (cognitive psychology) #Percolation threshold #Physics #Plant Water Relations and Carbon Dynamics #Remote Sensing in Agriculture #Shell (structure) #Smoothing #Statistical physics #Void (composites) #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stv879
published in Monthly Notices of the Royal Astronomical Society 450(3), 3239-3253 (Oxford University Press) · 17 pages, 20 figures; matches version published in MNRAS. ORIGAMI code available at http://icg.port.ac.uk/~falckb/
openalex publication_date 2015/05/12 · arxiv created 2015/05/13 · arxiv updated 2015/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the nature of voids defined as single-stream regions that have not undergone shell-crossing. We use origami to determine the cosmic web morphology of each dark matter particle in a suite of cosmological N-body simulations, which explicitly calculates whether a particle has crossed paths with others along multiple sets of axes and does not depend on a parameter or smoothing scale. The theoretical picture of voids is that of expanding underdensities with borders defined by shell-crossing. We find instead that locally underdense single-stream regions are not bounded on all sides by multi-stream regions, thus they percolate, filling the simulation volume; we show that the set of multi-stream particles also percolates. This percolation persists to high resolution, where the mass fraction of single-stream voids is low, because the volume fraction remains high; we speculate on the fraction of collapsed mass in the continuum limit of infinite resolution. By introducing a volume threshold parameter to define underdense void ‘cores’, we create a catalogue of origami voids which consist entirely of single-stream particles and measure their percolation properties, volume functions, and average densities.