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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731457.0, MPI für Astronomie / Publikationen_mpia
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
Authors:Zhu, L.; Romanowsky, A. J.; van de Ven, G.; Long, R. J.; Watkins, L. L.; Pota, V.; Napolitano, N. R.; Forbes, D. A.; Brodie, J.; Foster, C.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Monthly Notices of the Royal Astronomical Society
Issue / Number:4
Start Page:4001
End Page:4017
Audience:Not Specified
Abstract / Description:We construct a suite of discrete chemo-dynamical models of the giant elliptical galaxy NGC 5846. These models are a powerful tool to constrain both the mass distribution and internal dynamics of multiple tracer populations. We use Jeans models to simultaneously fit stellar kinematics within the effective radius Re, planetary nebula (PN) radial velocities out to 3 Re, and globular cluster (GC) radial velocities and colours out to 6 Re. The best-fitting model is a cored dark matter halo which contributes ˜10 per cent of the total mass within 1 Re, and 67 per cent ± 10 per cent within 6 Re, although a cusped dark matter halo is also acceptable. The red GCs exhibit mild rotation with vmax0 ˜ 0.3 in the region R > Re, aligned with but counter-rotating to the stars in the inner parts, while the blue GCs and PNe kinematics are consistent with no rotation. The red GCs are tangentially anisotropic, the blue GCs are mildly radially anisotropic, and the PNe vary from radially to tangentially anisotropic from the inner to the outer region. This is confirmed by general made-to-measure models. The tangential anisotropy of the red GCs in the inner regions could stem from the preferential destruction of red GCs on more radial orbits, while their outer tangential anisotropy - similar to the PNe in this region - has no good explanation. The mild radial anisotropy of the blue GCs is consistent with an accretion scenario.
Free Keywords:galaxies: individual: NGC 5846; galaxies: kinematics and dynamics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stw1931
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