The Magellanic Stream in Modified Newtonian Dynamics

The dynamics of the Magellanic Stream (MS) as a series of clouds extending from the Magellanic Clouds (MCs) to the south Galactic pole is affected by the distribution and the amount of matter in the Milky Way. We calculate the gravitational effect of the Galactic disk on the MS in the framework of modified Newtonian dynamics(MOND) and compare with observations of the Stream’s radial velocity. We consider the tidal force of the Galaxy, which strips material from the MCs to form the MS, and, using a no-halo model of the Galaxy, we ignore the effect of the drag of the Galactic halo on the MS. We also compare the MONDian dynamics with that in logarithmic and power-law dark halo models and show that the MOND theory seems plausible for describing the dynamics of satellite galaxies such as the MCs. Finally, we perform a maximum likelihood analysis to obtain the best MOND parameters for the Galactic disk. Subject headings: dark matter –Galaxy: halo –gravitation – Magellanic stream – MOND.