Modeling Turbulence in Galactic Centers

TL;DR

This paper introduces a new turbulence injection method for simulating the complex, high-velocity dispersion environment of galactic centers, demonstrated through a simplified model of the Milky Way's CMZ.

Contribution

A novel Fourier forcing module integrated into SPH simulations to drive turbulence, enabling long-term evolution studies of galactic center gas dynamics.

Findings

Turbulence induces flocculent spiral patterns similar to large-scale simulations.

The method balances gas self-gravity, allowing extended simulation times.

Inward gas migration observed, consistent with previous studies.

Abstract

Turbulence is a prevalent phenomenon in the interstellar medium, and in particular, the environment at the centers of galaxies. For example, detailed observations of the Milky Way's Central Molecular Zone (CMZ) revealed that it has a complex and turbulent structure. Turbulence on galactic scales is often modeled using star formation and feedback. However, these effects do not appear to be sufficient for explaining the high-velocity dispersion observed in the CMZ, indicating that additional gas-stirring processes are likely to be operating. Here we introduce a proof-of-concept method to drive turbulence in gas that orbits under the influence of a galactic potential. Instead of relying on a particular physical mechanism, we have adopted a Fourier forcing module and have applied it using a Smoothed Particle Hydrodynamics code. To test our method, we performed simulations of a simplistic model of the CMZ. Our turbulence injection method is capable of balancing the self-gravity of the gas, which allows us to run the simulations for long timescales and thereby follow the evolution of the CMZ. Our results show that turbulence induces a flocculent spiral pattern in our model, analogous to that found in galactic-scale simulations. Furthermore, we find that our turbulence injection method induces inward migration of gas, a result consistent with previous numerical simulations. We submit that this injection method is a promising new tool to simulate turbulence in galactic centers.