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A halo expansion technique for approximating simulated dark matter haloes.

Lowing, B. and Jenkins, A. R. and Eke, V. and Frenk, C. (2011) 'A halo expansion technique for approximating simulated dark matter haloes.', Monthly notices of the Royal Astronomical Society., 416 (4). pp. 2697-2711.


We apply a basis function expansion method to create a time-evolving density/potential approximation of the late growth of simulated N-body dark matter haloes. We demonstrate how the potential of a halo from the Aquarius Project can be accurately represented by a small number of basis functions, and show that the halo expansion (HEX) method provides a way to replay simulations. We explore the level of accuracy of the technique as well as some of its limitations. We find that the number of terms included in the expansion must be large enough to resolve the large-scale distribution and shape of the halo but, beyond this, additional terms result in little further improvement. Particle and subhalo orbits can be integrated in this realistic, time-varying halo potential approximation, at much lower cost than the original simulation, with high fidelity for many individual orbits, and a good match to the distributions of orbital energy and angular momentum. Statistically, the evolution of structural subhalo properties, such as mass, half-mass radius and characteristic circular velocity, are very well reproduced in the HEX approximation over several Gyr. We demonstrate an application of the technique by following the evolution of an orbiting subhalo at much higher resolution than can be achieved in the original simulation. Our method represents a significant improvement over commonly used techniques based on static analytical descriptions of the halo potential.

Item Type:Article
Keywords:Methods: numerical, Galaxies: haloes, Dark matter.
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2011 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:29 January 2015
Date of first online publication:October 2011
Date first made open access:No date available

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