A genetic approach to the history of the Magellanic Clouds

Abstract

The history of the Magellanic Clouds is investigated using N-body hydrodynamic simulations where the initial conditions are set by a genetic algorithm. This technique allows us to identify possible orbits for the Magellanic Clouds around the Milky Way, by directly comparing the simulations with observational constraints. We explore the parameter space of the interaction between the Magellanic Clouds and the MilkyWay, considering as free parameters the proper motions of the Magellanic Clouds, the virial mass and the concentration parameter (c) of the Galactic dark matter halo. The best orbital scenarios presented here are considered with two different sets of parameters for the Milky Way disc and bulge components. The total circular velocity at the Sun's position (R{N-ary circled plus operator} = 8.5 kpc) is directly calculated from the rotation curve of the corresponding Galactic mass model. Our analysis suggests that the Magellanic Clouds have orbited inside the virial radius of the Milky Way for at least 3 Gyr, even for lowmass haloes. However, this is possible only with high values for the concentration parameter (c ≥ 20). In both orbital models presented here, the mutual interaction between theMagellanic Clouds is able to reproduce the observed features of the Magellanic System.