Serbian Astronomical Journal (Dec 2008)
The Total Mass of the Early-Type Galaxy NGC 4649 (M60)
Abstract
In this paper the problem of the total mass and the total mass-to-light ratio of the early-type galaxy NGC~4649 (M60) is analyzed. Use is made of two independent techniques: the X-ray methodology which is based on the temperature of the X-ray halo of NGC~4649 and the tracer mass estimator (TME) which uses globular clusters (GCs) observed in this galaxy. The mass is calculated in Newtonian and MOdified Newtonian Dynamics (MOND) approaches and it is found that inside 3 effective radii ($R_e$) there is no need for large amounts of dark matter. Beyond $3R_e$ the dark matter starts to play important dynamical role. The possible reasons for the discrepancy between the estimates of the total mass based on X-rays and TME in the outer regions of NGC~4649 are also discussed.
