Total mass slopes and enclosed mass constrained by globular cluster system dynamics

Abstract

The goal of this work is to probe the total mass distribution of early-type galaxies with globular clusters (GCs) as kinematic tracers, by constraining the parameters of the profile with a flexible modelling approach. To that end, we leverage the extended spatial distribution of GCs from the SLUGGS survey ($⟨R_{\mathrm{GC},\max }⟩\sim 8R_{\mathrm{e}}$) in combination with discrete dynamical modelling. We use discrete Jeans anisotropic modelling in cylindrical coordinates to determine the velocity moments at the location of the GCs in our sample. We use a Bayesian framework to determine the best-fit parameters of the total mass density profile and orbital properties of the GC systems. We find that the orbital properties (anisotropy and rotation of the dispersion-dominated GC systems) minimally impact the measurements of the inner slope and enclosed mass, while a strong presence of dynamically-distinct subpopulations or low numbers of kinematic tracers can bias the results. Owing to the large spatial extent of the tracers our method is sensitive to the intrinsic inner slope of the total mass profile and we find $\overline{\alpha }=-1.88\pm 0.01$ for 12 galaxies with robust measurements. To compare our results with literature values we fit a single power-law profile to the resulting total mass density. In the radial range 0.1-4~$R_{\mathrm{e}}$ our measured slope has a value of $⟨{\gamma }_{\mathrm{tot}}⟩=-2.22\pm 0.14$ and is in good agreement with the literature.

17 pages, 13 Figures, 8 Tables, Accepted for publication in A&A

References in corpus (24)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The hierarchical formation of the brightest cluster galaxies
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early Type Galaxies
• The SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS): Sample definition, methods, and initial results
• The ACS Fornax Cluster Survey. I. Introduction to the Survey and Data Reduction Procedures
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. IV. Alpha Element Distributions in Milky Way Dwarf Satellite Galaxies
• Small scatter and nearly-isothermal mass profiles to four half-light radii from two-dimensional stellar dynamics of early-type galaxies
• Globular Cluster Systems in Brightest Cluster Galaxies: A Near-Universal Luminosity Function?
• Globular Cluster Systems in Brightest Cluster Galaxies. III: Beyond Bimodality
• Systematic variations of central mass density slopes in early-type galaxies
• Breaking Beta: A comparison of mass modelling methods for spherical systems
• The SLUGGS Survey: a catalog of over 4000 globular cluster radial velocities in 27 nearby early-type galaxies
• A discrete chemo-dynamical model of the giant elliptical galaxy NGC 5846: dark matter fraction, internal rotation and velocity anisotropy out to six effective radii
• The accretion histories of brightest cluster galaxies from their stellar population gradients
• The SLUGGS Survey: Multi-population dynamical modelling of the elliptical galaxy NGC 1407 from stars and globular clusters
• Total mass density slopes of early-type galaxies using Jeans dynamical modelling at redshifts $0.29<z<0.55$
• Study of gravitational fields and globular cluster systems of early-type galaxies
• Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. II. Globular Cluster Candidates and their Mass-Metallicity Relation
• Extended Star Clusters in NGC 1023 from HST/ACS Mosaic Imaging
• The MAGPI Survey: Impact of environment on the total internal mass distribution of galaxies in the last 5 Gyr
• What to expect when using globular clusters as tracers of the total mass distribution in Milky Way-mass galaxies

Cited by in corpus (1)

• Shapes of dark matter haloes with discrete globular cluster dynamics: The example of NGC 5128 (Centaurus A)