What to expect from dynamical modelling of galactic haloes II: the spherical Jeans equation

Abstract

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 the previous study of Wang et al. (2017) 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.

13 pages, 9 figures, accepted by MNRAS

References in corpus (18)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
• The mass distribution and gravitational potential of the Milky Way
• The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
• On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution
• The Cold Dark Matter Halos of Local Group Dwarf Spheroidals
• Kinematics of the stellar halo and the mass distribution of the Milky Way using BHB stars
• The Mass Profile of the Galaxy to 80 kpc
• HBT+: an improved code for finding subhalos and building merger trees in cosmological simulations
• The distribution function of dark matter in massive haloes
• Orbits of massive satellite galaxies: II. Bayesian Estimates of the Milky Way and Andromeda masses using high precision astrometry and cosmological simulations
• Creating mock catalogues of stellar haloes from cosmological simulations
• Joint constraints on the Galactic dark matter halo and Galactic Centre from hypervelocity stars
• Subhalo statistics of galactic halos: beyond the resolution limit
• The Milky Way's circular velocity curve and its constraint on the Galactic mass with RR Lyrae stars
• Determination of Dark Matter Halo Mass from Dynamics of Satellite Galaxies
• Jeans that fit: weighing the mass of the Milky Way analogues in the $\Lambda \mathrm{CDM}$ universe

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