Polytropic model fits to the globular cluster NGC 2419 in Modified Newtonian Dynamics

Abstract

We present an analysis of the globular cluster NGC 2419, using a polytropic model in Modified Newtonian Dynamics (MOND) to reproduce recently published high quality data of the structure and kinematics of the system. We show that a specific MOND polytropic model of NGC 2419 suggested by a previous study can be completely ruled out by the data. Furthermore, the highest likelihood fit polytrope in MOND is a substantially worse model (by a factor of approximately 5000) than a Newtonian Michie model studied in an earlier contribution by Ibata et al. (2011). We conclude that the structure and dynamics of NGC 2419 favor Newtonian dynamics and do indeed challenge the MOND theory.