Towards a Holistic View of the Origin of Multiple Stellar Populations in Globular Clusters

The origin of multiple stellar populations (MPs) in globular clusters (GCs) is one of the most puzzling issues of stellar astrophysics. Many attempts have been done both from observational and theoretical studies to unveil the enigma of their formation but, so far, a clear picture is still lacking.

In the upcoming years, new data will be available from ongoing surveys but also from new facilities such as James Webb Space Telescope. We will have access with unprecedented detail to the high-z Universe, where recent studies have detected systems likely being proto-GCs.

With this project, we propose to model, through 3D radiation-hydrodynamic simulations, the very early stages of GC formation studying the interplay between various physical ingredients like stellar feedback, gravity and cluster rotation, tracing various chemical elements like iron and helium. The goal of the project is to point towards a complete understanding of the origin of MP testing the feasibility of the asymptotic giant branch scenario, the most popular model proposed to explain the formation of GCs.

We will model the feedback from massive stars when they are still embedded in the gas rich cloud they formed from to derive the timescales of gas expulsion and determine whether star formation can take place during this phase. Such study will be crucial to verify whether massive stellar clusters could have retained part of the leftover gas which was then used to form new iron-enhanced stars. We aim at shedding light on the role of Type Ia SNe on MPs formation which is still a much debated topic, focusing on the iron enrichment they produce. We will then study the role of cluster rotation whose evolution has been found to depend on the assumed scenario for GC formation, and will therefore help in putting new constraints on them.

HPC resources are fundamental to perform such a large number of simulations at very high resolution.

This series of simulations will be crucial to interpret the available observational data and to drive future observational studies. The understanding of this eluding phenomenon is of great importance for many astrophysical issues like stellar evolution, nucleosynthesis, star formation in the dense early universe, the role of stellar dynamics on the formation of exotic stellar objects like binary black holes responsible for the emission of gravitational waves, the role of proto-GCs in the cosmic reionization and in galaxy formation.