The three dimensional skeleton: tracing the filamentary structure of the universe

Abstract

The skeleton formalism aims at extracting and quantifying the filamentary structure of the universe is generalized to 3D density fields; a numerical method for computating a local approximation of the skeleton is presented and validated here on Gaussian random fields. This method manages to trace well the filamentary structure in 3D fields such as given by numerical simulations of the dark matter distribution on large scales and is insensitive to monotonic biasing. Two of its characteristics, namely its length and differential length, are analyzed for Gaussian random fields. Its differential length per unit normalized density contrast scales like the PDF of the underlying density contrast times the total length times a quadratic Edgeworth correction involving the square of the spectral parameter. The total length scales like the inverse square smoothing length, with a scaling factor given by 0.21 (5.28+ n) where n is the power index of the underlying field. This dependency implies that the total length can be used to constrain the shape of the underlying power spectrum, hence the cosmology. Possible applications of the skeleton to galaxy formation and cosmology are discussed. As an illustration, the orientation of the spin of dark halos and the orientation of the flow near the skeleton is computed for dark matter simulations. The flow is laminar along the filaments, while spins of dark halos within 500 kpc of the skeleton are preferentially orthogonal to the direction of the flow at a level of 25%.

17 pages, 11 figures, submitted to MNRAS

References in corpus (4)

• Spin alignment of dark matter haloes in filaments and walls
• The Three-Point Correlation Function of Luminous Red Galaxies in the Sloan Digital Sky Survey
• Topology of large-scale structure in the 2dF Galaxy Redshift Survey
• Dynamical flows through Dark Matter Haloes II: one and two points statistics at the virial radius

Cited by in corpus (7)

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• The spin and orientation of dark matter halos within cosmic filaments
• Small-Angle CMB Temperature Anisotropies Induced by Cosmic Strings
• Environmental dependence in the ellipsoidal collapse model
• The fully connected N-dimensional skeleton: probing the evolution of the cosmic web
• On the Onset of Stochasticity in $\Lambda$CDM Cosmological Simulations
• Statistical properties of the linear tidal shear