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Orbital parameters of infalling satellite haloes in the hierarchical ΛCDM model.

Jiang, L. and Cole, S. and Sawala, T. (2015) 'Orbital parameters of infalling satellite haloes in the hierarchical ΛCDM model.', Monthly notices of the Royal Astronomical Society., 448 (2). pp. 1674-1686.


We present distributions of orbital parameters of infalling satellites of Λ cold dark matter (ΛCDM) haloes in the mass range 1012–1014 M⊙, which represent the initial conditions for the subsequent evolution of substructures within the host halo. We use merger trees constructed in a high-resolution cosmological N-body simulation to trace satellite haloes, and identify the time of infall. We find significant trends in the distribution of orbital parameters with both the host halo mass and the ratio of satellite-to-host halo masses. For all host halo masses, satellites whose infall mass is a larger fraction of the host halo mass have more eccentric, radially biased orbits. At fixed satellite-to-host halo mass ratio, high-mass haloes are biased towards accreting satellites on slightly more radial orbits. To characterize the orbital distributions fully requires fitting the correlated bivariate distribution of two chosen orbital parameters (e.g. radial and tangential velocity or energy and angular momentum). We provide simple fits to one choice of the bivariate distributions, which when transformed faithfully, captures the behaviour of any of the projected one-dimensional distributions.

Item Type:Article
Keywords:Methods: numerical, Galaxies: haloes, Cosmology: theory, Dark matter.
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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:10 February 2015
Date deposited:16 April 2015
Date of first online publication:April 2015
Date first made open access:No date available

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