Candidate super star cluster progenitor gas clouds possibly triggered by close passage to Sgr A*

TL;DR

This paper presents a method to identify potential progenitor gas clouds of super star clusters in the Galactic center, suggesting their formation may be triggered by close passages near Sgr A*, providing insights into extreme star formation conditions.

Contribution

The study introduces a new technique to find YMC progenitor clouds and proposes a triggering scenario involving close passages near Sgr A* in the Galactic center.

Findings

Identified three potential YMC progenitor clouds in the inner Galaxy.

Found no similar clouds elsewhere in the Galaxy despite extensive searches.

Proposed a triggering mechanism involving gas streams near Sgr A*.

Abstract

Super star clusters are the end product of star formation under the most extreme conditions. As such, studying how their final stellar populations are assembled from their natal progenitor gas clouds can provide strong constraints on star formation theories. An obvious place to look for the initial conditions of such extreme stellar clusters are gas clouds of comparable mass and density, with no star formation activity. We present a method to identify such progenitor gas clouds and demonstrate the technique for the gas in the inner few hundred pc of our Galaxy. The method highlights three clouds in the region with similar global physical properties to the previously identified extreme cloud, G0.253+0.016, as potential young massive cluster (YMC) precursors. The fact that four potential YMC progenitor clouds have been identified in the inner 100 pc of the Galaxy, but no clouds with similar properties have been found in the whole first quadrant despite extensive observational efforts, has implications for cluster formation/destruction rates across the Galaxy. We put forward a scenario to explain how such dense gas clouds can arise in the Galactic centre environment, in which YMC formation is triggered by gas streams passing close to the minimum of the global Galactic gravitational potential at the location of the central supermassive black hole, Sgr A*. If this triggering mechanism can be verified, we can use the known time interval since closest approach to Sgr A* to study the physics of stellar mass assembly in an extreme environment as a function of absolute time.