Title：Galaxy assembly revealed by the life cycle of star clusters

Speaker：Yingtian Chen（University of Michigan Department of Astronomy）

Time：May 31th, 3-4 pm, Friday

Location: Small conference room 3rd floor

Abstract：

The life cycle of a star cluster can be broken into three epochs: 1) the birth of the cluster; 2) the long phase when the cluster evolves in gravitational equilibrium, gradually losing stars; and 3) the death of the cluster when it dissolves into a stream of stars. The clusters in the first epoch directly record the initial properties inherited from the host galaxy. The evolved clusters during the second epoch are often old, massive, and gravitationally bound, observationally identified as globular clusters (GCs); Although their properties may have evolved from the initial values, GCs still provide comprehensive information about the galaxy’s assembly history. In the last epoch of cluster evolution, the morphology and kinematics of stellar streams encode the gravitational interaction with the host galaxy's mass content and substructures. Yet, the link between the galaxy's assembly history and the properties of the star clusters still remains unclear due to limited observations outside the Milky Way (MW), inspiring numerical modeling. However, existing models for different epochs are poorly connected and calibrated due to the distinct physical processes and scales governing these stages. In this talk, I will discuss ongoing efforts to address these complexities: We have developed numerical models specifically optimized for the three epochs using hydrodynamic simulations and semi-analytical modeling methods, which help build a unified understanding of the life cycle of star clusters. I will also describe how to justify and improve the existing pipelines revealing galaxy assembly from star clusters using mock observations of model outputs.

CV：I am a Ph.D. candidate at the University of Michigan Department of Astronomy, where I work with Prof. Oleg Gnedin. Before coming to Michigan, I received my B.S. degree at Peking University School of Physics in 2020. I am a theorist trying to unravel the nature of star cluster formation and evolution. In small scales, I run simulations to study the hierarchical assembly of star clusters from molecular clouds. In large scales, I develop post-processing models on existing cosmological simulation suites to follow the lifespan of globular clusters from their birth to death across more than ten billion years. View yingtianchen.com for more details.