Hydrodynamical simulations of Galactic fountains I: evolution of single fountains

TL;DR

This study uses 3D hydrodynamical simulations to analyze the evolution of galactic fountains driven by supernovae, revealing their limited impact on large-scale chemical distribution in the Milky Way.

Contribution

It provides detailed modeling of single galactic fountains, showing their dynamics and localized effects on metal redistribution, a novel focus on individual fountain evolution.

Findings

Fountains eject gas up to ~2 kpc height

Most ejected gas falls back within 0.5 kpc of origin

Localized fountains do not significantly alter large-scale metallicity gradients

Abstract

The ejection of the gas out of the disk in late-type galaxies is related to star formation and is due mainly to Type II supernovae. In this paper we studied in detail the development of the Galactic fountains in order to understand their dynamical evolution and their influence in the redistribution of the freshly delivered metals over the disk. To this aim, we performed a number of 3D hydrodynamical radiative cooling simulations of the gas in the Milky Way where the whole Galaxy structure, the Galactic differential rotation and the supernovae explosions generated by a single OB association are considered. A typical fountain powered by 100 Type II supernovae may eject material up to $\sim 2$ kpc which than collapses back mostly in form of dense, cold clouds and filaments. The majority of the gas lifted up by the fountains falls back on the disk remaining within a radial distance $\Delta R=0.5$ kpc from the place where the fountain originated. This localized circulation of disk gas does not influence the radial chemical gradients on large scale, as required by the chemical models of the Milky Way which reproduce the metallicity distribution without invoking large fluxes of metals. Simulations of multiple fountains fuelled by Type II supernovae of different OB associations will be presented in a companion paper.