Journal Article

Crawling the cosmic network: exploring the morphology of structure in the galaxy distribution

Nicholas A. Bond, Michael A. Strauss and Renyue Cen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 406, issue 3, pages 1609-1628
Published in print August 2010 | ISSN: 0035-8711
Published online August 2010 | e-ISSN: 1365-2966 | DOI:
Crawling the cosmic network: exploring the morphology of structure in the galaxy distribution

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Although coherent large-scale structures such as filaments and walls are apparent to the eye in galaxy redshift surveys, they have so far proven difficult to characterize with computer algorithms. This paper presents a procedure that uses the eigenvalues and eigenvectors of the Hessian matrix of the galaxy density field to characterize the morphology of large-scale structure. By analysing the smoothed density field and its Hessian matrix, we can determine the types of structure – walls, filaments or clumps – that dominate the large-scale distribution of galaxies as a function of scale. We have run the algorithm on mock galaxy distributions in a Λcold dark matter cosmological N-body simulation and the observed galaxy distributions in the Sloan Digital Sky Survey. The morphology of structure is similar between the two catalogues, both being filament-dominated on 10–20 h−1 Mpc smoothing scales and clump-dominated on 5 h−1 Mpc scales. There is evidence for walls in both distributions, but walls are not the dominant structures on scales smaller than ∼ 25 h−1 Mpc. Analysis of the simulation suggests that, on a given comoving smoothing scale, structures evolve with time from walls to filaments to clumps, where those found on smaller smoothing scales are further in this progression at a given time.

Keywords: methods: data analysis; surveys; cosmology: observations; large-scale structure of Universe

Journal Article.  10178 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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