Tracing the cosmic web

Noam I. Libeskind*, Rien van de Weygaert, Marius Cautun, Bridget Falck, Elmo Tempel, Tom Abel, Mehmet Alpaslan, Miguel A. Aragon-Calvo, Jaime E. Forero-Romero, Roberto Gonzalez, Stefan Gottloeber, Oliver Hahn, Wojciech A. Hellwing, Yehuda Hoffman, Bernard J. T. Jones, Francisco Kitaura, Alexander Knebe, Serena Manti, Mark Neyrinck, Sebastian E. NuzaNelson Padilla, Erwin Platen, Nesar Ramachandra, Aaron Robotham, Enn Saar, Sergei Shandarin, Matthias Steinmetz, Radu S. Stoica, Thierry Sousbie, Gustavo Yepes

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

The cosmic web is one of the most striking features of the distribution of galaxies and dark matter on the largest scales in the Universe. It is composed of dense regions packed full of galaxies, long filamentary bridges, flattened sheets and vast low-density voids. The study of the cosmic web has focused primarily on the identification of such features, and on understanding the environmental effects on galaxy formation and halo assembly. As such, a variety of different methods have been devised to classify the cosmic web - depending on the data at hand, be it numerical simulations, large sky surveys or other. In this paper, we bring 12 of these methods together and apply them to the same data set in order to understand how they compare. In general, these cosmic-web classifiers have been designed with different cosmological goals in mind, and to study different questions. Therefore, one would not a priori expect agreement between different techniques; however, many of these methods do converge on the identification of specific features. In this paper, we study the agreements and disparities of the different methods. For example, each method finds that knots inhabit higher density regions than filaments, etc. and that voids have the lowest densities. For a given web environment, we find a substantial overlap in the density range assigned by each web classification scheme. We also compare classifications on a halo-by-halo basis; for example, we find that 9 of 12 methods classify around a third of group-mass haloes (i.e. M-halo similar to 10(13.5) h(-1) M-circle dot) as being in filaments. Lastly, so that any future cosmic-web classification scheme can be compared to the 12 methods used here, we have made all the data used in this paper public.

Original languageEnglish
Pages (from-to)1195-1217
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number1
DOIs
Publication statusPublished - Jan-2018

Keywords

  • methods: data analysis
  • dark matter
  • large-scale structure of the Universe
  • cosmology: theory
  • LARGE-SCALE STRUCTURE
  • MASS ASSEMBLY GAMA
  • DARK-MATTER HALOES
  • SPIN ALIGNMENT
  • FILAMENTARY STRUCTURE
  • LOCAL UNIVERSE
  • SATELLITE GALAXIES
  • ANGULAR-MOMENTUM
  • COMPARISON PROJECT
  • INITIAL-CONDITIONS

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