In order to better understand the role that Galactic scale dynamical forces have on the properties of the Milky Way’s Galactic Center, we run high resolution hydrodynamical simulations to model the gas flows in the innermost few kiloparsecs. An immensely important component of the gravitational potential in the Galactic Center is the Milky Ways’ stellar bar, an elongated tube-like distribution of stars. The bar forces gas off of stable orbits and into the so-called dust lanes, which move mass from the inner Galactic Disk towards the CMZ. This bar-driven inflow is the primary means by which we believe the Galactic Center gains its mass. Our simulations are designed to isolate the dynamical effects from the bar’s potential on these gas flows and on the properties of gas in the CMZ, while excluding the effects of gas self-gravity and star formation physics (which have been explored in parallel work and shown not to have a significant effect on the inflow rate).
The dust lanes are very effective at moving gas from larger Galactocentric radii inwards, but not all the inflowing mass instantly becomes integrated into the CMZ! Some fraction will overshoot and might mislead observational estimates of the inflow. Using Monte Carlo tracer particles, we follow the evolution of parcels of gas as they flow along the dust lanes and explore the efficiency of this mechanism of inflow. This inefficiency can be used to modify observational estimates of the Galactic Center inflow rate, which in turn inform our understanding of how the CMZ evolves and how the supermassive black hole at the center of our Galaxy grows and interacts with its surroundings.
These same simulations offer the opportunity to explore the effects of the bar’s gravitational forces on the evolution of molecular clouds in the CMZ. In the same upcoming work, we will show how the density and rotational properties of such clouds are influenced by interactions with inflowing gas from the dust lanes. Once this paper is accepted, more will be summarized here!
H Perry Hatchfield 