The total mass of the early-type galaxy NGC 4649 (M60)

TL;DR

This study estimates the total mass and mass-to-light ratio of galaxy NGC 4649 using X-ray data and globular cluster observations, finding little dark matter within 3 effective radii but significant dark matter beyond that.

Contribution

It compares Newtonian and MOND models and discusses discrepancies between X-ray and TME mass estimates in the galaxy's outer regions.

Findings

No significant dark matter within 3Re

Dark matter becomes important beyond 3Re

Discrepancies between X-ray and TME estimates discussed

Abstract

In this paper we analyze the problem of the total mass and the total mass-to-light ratio of the early-type galaxy NGC 4649 (M60). We have used 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. We calculated the mass in Newtonian and MOdified Newtonian Dynamics (MOND) approaches and found that interior to 3 effective radii (Re) there is no need for large amounts of dark matter. Beyond 3Re dark matter starts to play important dynamical role. We also discuss 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.