Hydrodynamical simulations of Galactic fountains II: evolution of multiple fountains

TL;DR

This study uses 3D hydrodynamical simulations to analyze the behavior of galactic fountains, focusing on metal recycling, feedback effects, and the influence of external gas infall on halo gas dynamics.

Contribution

It provides detailed insights into the localized nature of fountain flows and their limited impact on disk chemical profiles, incorporating star formation feedback and external gas infall effects.

Findings

Fountains predominantly recycle metals locally near their origin.

Fountains have minimal effect on the radial chemical abundance profile.

External gas infall may slow halo gas rotation and reduce angular momentum transfer.

Abstract

Using 3D hydrodynamical simulations, we studied in detail the fountain flow and its dependence with several factors, such as the Galactic rotation, the distance to the Galactic center, and the presence of a hot gaseous halo. We have considered the observed size-frequency distribution of young stellar clusters within the Galaxy in order to appropriately fuel the multiple fountains in our simulations. The present work confirms the localized nature of the fountain flows: the freshly ejected metals tend to fall back close to the same Galactocentric region where they are delivered. Therefore, the fountains do not change significantly the radial profile of the disk chemical abundance. The multiple fountains simulations also allowed to consistently calculate the feedback of the star formation on the halo gas. Finally, we have also considered the possibility of mass infall from the intergalactic medium and its interaction with the clouds that are formed by the fountains. Though our simulations are not suitable to reproduce the slow rotational pattern that is typically observed in the halos around the disk galaxies, they indicate that the presence of an external gas infall may help to slow down the rotation of the gas in the clouds and thus the amount of angular momentum that they transfer to the coronal gas, as previously suggested in the literature.