Can spirals help the Milky Way 'breathe'? a quest with simulations and the Gaia mission

Gaia DR2 (along with earlier surveys) has revealed vertical breathing motions in the Milky Way, with stars on both sides of the Galactic mid-plane moving coherently towards or away from it. The full consensus about the driving mechanisms (external and/or internal) for these breathing motions is still missing till date. In this talk, first I will discuss the characteristics of such vertical breathing motions driven by spiral density waves by making use of a high-resolution, self-consistent simulation of a Milky Way-like galaxy, and how the amplitudes of the resulting breathing motions vary with stellar populations of different stellar ages. Further, I will briefly mention the excitation of breathing motions in case of fly-by encounters in disc galaxies, using a set of N-body models. Lastly, I will highlight our findings about the age variation of the vertical breathing motion of the Milky Way, obtained from the Gaia DR2, and what better understanding can be achieved with the recent Gaia DR3.