A discrete chemo-dynamical model of M87’s globular clusters: Kinematics extending to ∼ 400 kpc

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We study the mass distribution and kinematics of the giant elliptical galaxy M87 (NGC
4486) using discrete chemo-dynamical, axisymmetric Jeans equation modelling. Our catalogue comprises 894 globular clusters (GCs) extending to a projected radius of ∼ 430 kpc with line-of-sight velocities and colours, and Multi Unit Spectroscopic Explorer (MUSE) integral field unit data within the central 2.4 kpc of the main galaxy. The gravitational potential for our models is a combination of a luminous matter potential with a varying mass-to-light ratio for the main galaxy, a supermassive black hole and a dark matter (DM) potential with a cusped or cored DM halo. The best-fitting models with either a cusped or a cored DM halo show no significant differences and both are acceptable. We obtain a total mass of (2.16 ± 0.38) × 10 13 M within ∼ 400 kpc. By including the stellar mass-to-light ratio gradient, the DM fraction increases maj from ∼ 26 percent (with no gradient) to ∼ 73 percent within 1 R e (major axis of half-light maj isophote, 14.2 kpc), and from ∼ 84 percent to ∼ 94 percent within 5 R e (71.2 kpc). Red GCs have moderate rotation with V max /σ ∼ 0.4, and blue GCs have weak rotation with V max /σ ∼ 0.1. Red GCs have tangential velocity dispersion anisotropy, while blue GCs are consistent
with being nearly isotropic. Our results suggest that red GCs are more likely to be born in-situ, while blue GCs are more likely to be accreted.
Original languageEnglish
Number of pages20
Publication statusAccepted/In press - 23 Dec 2019


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