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

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY(2020)

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摘要
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 similar to 430 kpc with line-of-sight velocities and colours, and Multi Unit Spectroscopic Explorer 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) x 10(13) M-circle dot within similar to 400 kpc. By including the stellar mass-to-light ratio gradient, the DM fraction increases from similar to 26 per cent (with no gradient) to similar to 73 per cent within 1 R-e(maj) (major axis of half-light isophote, 14.2 kpc), and from similar to 84 per cent to similar to 94 per cent within 5 R-e(maj) (71.2 kpc). Red GCs have moderate rotation with V-max/sigma similar to 0.4, and blue GCs have weak rotation with V-max/sigma similar to 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.
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关键词
galaxies: individual: M87,galaxies: kinematics and dynamics
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