ECOGAL Highlight: Galactic scale models of star formation

ECOGAL Highlight: Galactic scale models of star formation

Galactic scale models of star formation focus on resolving how large-scale gas flows in spiral galaxies form the dense gas clouds where star formation occurs on scales 10,000 times smaller. The rate at which stars form in galaxies appears to be linked to the global as well as local properties. Using DiRAC, we have performed the largest-scale numerical simulations that can resolve the dense regions where stars form, and hence directly study the physics that drives star formation. We are using these simulations to understand how star formation is initiated, and what determines the resulting properties including why it has such a low efficiency (~1%).

Figure 1. The dense gas formed from a spiral shock is viewed perpendicular to the plane of the galaxy.

There also exist ‘special’ regions such as the centre of our Galaxy, where star formation is more exotic and primarily forms only very massive stars. Using realistic models for the galaxy’s gravity, we are studying the dynamics of gas clouds and how they can produced the observed structures and star formation events, including the young stars that orbit the super-massive black hole.

In order to construct a full theory of star formation, we need to also include additional physics of magnetic fields and the radiative and kinetic feedback processes from young stars. Constructing these self-consistent models, akin to modelling a full galactic ecology, requires the ability to model 100 to 1000 million individual elements in the galaxy and can only be performed with the HPC resources provided through DiRAC.

Figure 2. A gas cloud moving on an eccentric orbit in the Galactic Center is tidally sheared to form nearly complete stream.