期刊
ASTRONOMY & ASTROPHYSICS
卷 488, 期 3, 页码 873-877出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361:200809524
关键词
gravitation; galaxies : elliptical and lenticular, cD; galaxies : kinematics and dynamics; galaxies : halos; galaxies : individual : NGC 4649
资金
- Ministry of Science of the Republic of Serbia [146012]
Context. Regarding the significant interest in both dark matter and the application of MOND to early-type galaxies, we investigate the MOND theory by comparing its predictions, for models of constant mass-to-light ratio, with observational data of the early-type galaxy NGC 4649. Aims. We study whether measurements for NGC 3379 and NGC 1399 are typical of early-type systems and we test the assumption of a Newtonian constant M/L ratio underlying most of the published models. Methods. We employ the globular clusters of NGC 4649 as a mass tracer. The Jeans equation is calculated for both MOND and constant mass-to-light ratio assumptions. Spherical symmetry is assumed and the calculations are performed for both isotropic and anisotropic cases. Results. We found that both Jeans models with the assumption of a constant mass-to-light ratio and different MOND models provide good agreement with the observed values of the velocity dispersion. The most accurate fits of the velocity dispersion were obtained for the mass-to-light ratio in the B-band, which was equal to 7, implying that there is no need for significant amounts of dark matter in the outer parts (beyond 3 effective radii) of this galaxy. We also found that tangential anisotropies are most likely present in NGC 4649.
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