The Milky Way as modeled by Percolation and Superbubbles

TL;DR

This paper models the spiral structure of the Milky Way using percolation theory triggered by superbubbles from supernovae, comparing thermal and cold models with hydrodynamic simulations.

Contribution

It introduces two new models for superbubble evolution in the galaxy and compares them with hydrodynamic results, enhancing understanding of galactic structure formation.

Findings

Thermal and cold models match hydrodynamic simulations reasonably well.

The models successfully reproduce observed features like the Galactic Hole.

Simulation of specific structures like the Gould Belt aligns with observations.

Abstract

The spiral structure of the Milky Way can be simulated by adopting percolation theory, where the active zones are produced by the evolution of many supernova (SN). Here we assume conversely that the percolative process is triggered by superbubbles (SB), the result of multiple SNs. A first thermal model takes into account a bursting phase which evolves in a medium with constant density, and a subsequent adiabatic expansion which evolves in a medium with decreasing density along the galactic height. A second cold model follows the evolution of an SB in an auto-gravitating medium in the framework of the momentum conservation in a thin layer. Both the thermal and cold models are compared with the results of numerical hydro-dynamics. A simulation of GW~46.4+5.5, the Gould Belt, and the Galactic Plane is reported. An elementary theory of the image, which allows reproducing the hole visible at the center of the observed SB, is provided.