Not gone with the Wind: Survival of High-Velocity Molecular Clouds in the Galactic center

TL;DR

This study uses 3D simulations to show that magnetic fields help high-velocity molecular clouds survive and reach high altitudes in the Galactic center during starburst activity.

Contribution

It demonstrates that magnetic fields can protect and accelerate molecular clouds, explaining their observed high velocities and altitudes in the Galactic center.

Findings

Magnetic fields provide effective protection to molecular clouds.

Molecular clouds can reach ~1 kpc altitude with ~200 km/s velocity.

HVMC survival explained by magnetic shielding during starburst activity.

Abstract

High-velocity atomic clouds in the Galactic center have attracted significant attention due to their enigmatic formation process, which is potentially linked to the starburst or supermassive black hole activities in the region. Further, the discovery of high-velocity molecular clouds (HVMCs) presents a greater puzzle, because they are much denser and more massive. If the HVMCs were accelerated by the strong activities in the Galactic center, they are expected to be destroyed before they reach such a high velocity. To shed light on this phenomenon, we perform three-dimensional numerical simulations to investigate the origin and hydrodynamic evolution of HVMCs during a starburst in the Galactic center. We find that the presence of a magnetic field provides effective protection and acceleration to molecular clouds (MCs) within the galactic winds. Consequently, the MCs can attain latitudes of approximately 1 kpc with velocities around 200 km/s, consistent with the observed characteristics of HVMCs. The consistency of our findings across a wide parameter space supports the conclusion that HVMCs can indeed withstand the starburst environment in the Galactic center, providing valuable insights into their survival mechanisms.