Subhaloes going Notts: The subhalo-finder comparison project

Julian Onions, Alexander Knebe, Frazer R. Pearce, Stuart I. Muldrew, Hanni Lux, Steffen R. Knollmann, Yago Ascasibar, Peter Behroozi, Pascal Elahi, Jiaxin Han, Michal MacIejewski, Manuel E. Merchán, Mark Neyrinck, Andrés N. Ruiz, Mario A. Sgró, Volker Springel, Dylan Tweed

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


We present a detailed comparison of the substructure properties of a single Milky Way sized dark matter halo from the Aquarius suite at five different resolutions, as identified by a variety of different (sub)halo finders for simulations of cosmic structure formation. These finders span a wide range of techniques and methodologies to extract and quantify substructures within a larger non-homogeneous background density (e.g. a host halo). This includes real-space-, phase-space-, velocity-space- and time-space-based finders, as well as finders employing a Voronoi tessellation, Friends-of-Friends techniques or refined meshes as the starting point for locating substructure. A common post-processing pipeline was used to uniformly analyse the particle lists provided by each finder. We extract quantitative and comparable measures for the subhaloes, primarily focusing on mass and the peak of the rotation curve for this particular study. We find that all of the finders agree extremely well in the presence and location of substructure and even for properties relating to the inner part of the subhalo (e.g. the maximum value of the rotation curve). For properties that rely on particles near the outer edge of the subhalo the agreement is at around the 20per cent level. We find that the basic properties (mass and maximum circular velocity) of a subhalo can be reliably recovered if the subhalo contains more than 100 particles although its presence can be reliably inferred for a lower particle number limit of 20. We finally note that the logarithmic slope of the subhalo cumulative number count is remarkably consistent and <1 for all the finders that reached high resolution. If correct, this would indicate that the larger and more massive, respectively, substructures are the most dynamically interesting and that higher levels of the (sub)subhalo hierarchy become progressively less important.

Original languageEnglish (US)
Pages (from-to)1200-1214
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Jun 2012
Externally publishedYes


  • Cosmology: theory
  • Dark matter
  • Galaxies: evolution
  • Galaxies: haloes
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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