A PRIMAL view of the Milky Way, made possible by Gaia and M2M modelling

Abstract

We have developed our original made-to-measure (M2M) algorithm, primal, with the aim of modelling the Galactic disc from upcoming Gaia data. From a Milky Way like N-body disc galaxy simulation, we have created mock Gaia data using M0III stars as tracers, taking into account extinction and the expected Gaia errors. In primal, observables calculated from the N-body model are compared with the target stars, at the position of the target stars. Using primal, the masses of the N-body model particles are changed to reproduce the target mock data, and the gravitational potential is automatically adjusted by the changing mass of the model particles. We have also adopted a new resampling scheme for the model particles to keep the mass resolution of the N-body model relatively constant. We have applied primalto this mock Gaia data and we show that primalcan recover the structure and kinematics of a Milky Way like barred spiral disc, along with the apparent bar structure and pattern speed of the bar despite the galactic extinction and the observational errors.