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N-body dark matter haloes with simple hierarchical histories

Jiang, Lilian; Helly, John; Cole, Shaun; Frenk, Carlos

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Lilian Jiang


We present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly hierarchical. One advantage of these `Dhaloes' over the commonly used friends-of-friends (FoF) haloes is that they retain their individual identity in the cases when FoF haloes are artificially merged by tenuous bridges of particles or by an overlap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi-analytic galaxy formation model, GALFORM. Applying the Dhalo construction to the Λ cold dark matter Millennium II Simulation, we find that approximately 90 per cent of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10 per cent are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF haloes. Approximately 80 per cent of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes, all three types have similar concentration-M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions.


Jiang, L., Helly, J., Cole, S., & Frenk, C. (2014). N-body dark matter haloes with simple hierarchical histories. Monthly Notices of the Royal Astronomical Society, 440(3), 2115-2135.

Journal Article Type Article
Acceptance Date Feb 24, 2014
Online Publication Date Apr 4, 2014
Publication Date May 21, 2014
Deposit Date Apr 11, 2014
Publicly Available Date Apr 14, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 440
Issue 3
Pages 2115-2135
Keywords Methods: numerical, Galaxies: haloes, Cosmology: theory, Dark matter.


Published Journal Article (3.1 Mb)

Copyright Statement
This article has been published in the Monthly Notices of the Royal Astronomical Society. © 2014 The Authors
Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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