Causes of rotation variability in EDGE-formed nuclear star clusters

Identify the physical mechanisms that generate rotation in nuclear star clusters formed in the EDGE simulations of low-mass dwarf galaxies and determine why some nuclear star clusters exhibit strong rotation while others show little or no rotation.

Background

In the Stellar kinematics analysis, the authors compare the rotational signatures of nuclear star clusters (NSCs) across different EDGE simulations. They report that the Different Seed simulation displays the strongest rotation, reaching approximately 4 km/s at 100–200 pc from the dwarf’s center, while the Later simulation shows weaker rotation and the Reference simulation shows no detectable rotation signal.

This variability suggests that rotation in NSCs depends sensitively on the conditions of star formation and the merger-driven starburst that forms the NSC, but the specific causes and controlling parameters are not yet understood. The authors explicitly defer a detailed investigation of these causes to future work, framing it as an unresolved question.