Wang, W. and Han, J. and Cole, S. and More, S. and Frenk, C. and Schaller, M. (2018) 'What to expect from dynamical modelling of galactic haloes II : the spherical Jeans equation.', Monthly notices of the Royal Astronomical Society., 476 (4). pp. 5669-5680.
The spherical Jeans equation (SJE) is widely used in dynamical modelling of the Milky Way (MW) halo potential. We use haloes and galaxies from the cosmological Millennium-II simulation and hydrodynamical APOSTLE simulations to investigate the performance of the SJE in recovering the underlying mass profiles of MW mass haloes. The best-fitting halo mass and concentration parameters scatter by 25% and 40% around their input values, respectively, when dark matter particles are used as tracers. This scatter becomes as large as a factor of 3 when using star particles instead. This is significantly larger than the estimated statistical uncertainty associated with the use of the SJE. The existence of correlated phase-space structures that violate the steady state assumption of the SJE as well as non-spherical geometries are the principal sources of the scatter. Binary haloes show larger scatter because they are more aspherical in shape and have a more perturbed dynamical state. Our results confirm that the number of independent phase-space structures sets an intrinsic limiting precision on dynamical inferences based on the steady state assumption. Modelling with a radius-independent velocity anisotropy, or using tracers within a limited outer radius, result in significantly larger scatter, but the ensemble-averaged measurement over the whole halo sample is approximately unbiased.
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||https://doi.org/10.1093/mnras/sty706|
|Publisher statement:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||11 March 2018|
|Date deposited:||06 April 2018|
|Date of first online publication:||15 March 2018|
|Date first made open access:||No date available|
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