Effects of turbulence in the Circumnuclear Disk

TL;DR

This study uses 3D simulations to explore how turbulence impacts the structure of the Galactic Center's Circumnuclear Disk, revealing transient gas streams and questioning the nature of observed clumps.

Contribution

It introduces a turbulence driving method in simulations to analyze the CND's response, highlighting the formation of transient structures and the potential observational artifacts.

Findings

Large-scale turbulence induces transient gas streams.

Transient structures do not necessarily mean the CND is transient.

Observed clumps may be artifacts of observational limitations.

Abstract

A Circumnuclear Disk (CND) of molecular gas occupies the central few parsecs of the Galactic Center. It is likely subject to turbulent disruptions from violent events in its surrounding environment, but the effect of such perturbations has not yet been investigated in detail. Here we perform 3D, N-body/smoothed particle hydrodynamic (SPH) simulations with an adapted general turbulence driving method to investigate the CND's structural evolution, in particular its reaction to varied scales of injected turbulence. We find that, because of shear flow in the disk, transient arcs of gas (streams) naturally arise when turbulence is driven on large scales (up to ~4 pc), as might occur when a supernova blast wave encounters the CND. Because energetic events arise naturally and often in the central parsecs of our Galaxy, this result suggests that the transient structures that characterize the CND do not imply that the CND itself is a transient structure. We also note that features similar to the density concentrations, or "clumps", detailed in literature emerge when we account for the observed orientation of the disk and for the spatial resolution of observations. As such, clumps could be an artifact of observational limitations.