Periodic Reporting for period 3 - Multi-Pop (Fulfilling the Potential of Globular Clusters as Tracers of Cosmological Mass Assembly)
Reporting period: 2018-09-01 to 2020-02-29
Our understanding of GCs and their formation has undergone a radical change in the past two decades. First, it is now clear that while traditionally thought of as the quintessential simple stellar populations (i.e. all stars within a cluster have the same chemical abundances and age within some small tolerance), globular clusters host multiple stellar populations with spreads in He, many light elements (e.g. Na, O, Al) and even Fe in a few cases. Secondly, GCs, once thought to only be able to form in the special conditions present in the early Universe, are now known to be still forming today (known as Young Massive Clusters - YMCS). These two facts have opened up a new window into the interconnectedness of GC and galaxy formation and co-evolution.
In this project we will quantitatively test current GC formation models with observations of YMCs, as well as organise what is known of the stellar populations within GCs (e.g. abundance spreads, CMD morphologies), providing, for the first time, a global view (i.e. which characteristics are specific to individual GCs and which are common to all GCs). These results, when combined with what is known about massive cluster formation in the local universe, will provide an unprecedented opportunity to use GCs to constrain the hierarchical assembly of galaxies.
Along side this work, we have been implementing the inclusion of globular cluster formation and evolution in cosmological hydrodynamical simulations (E-MOSAICS). This is the first time that a self-consistent description of GC formation and evolution, along with the local and global properties of the host galaxy has been undertaken. We plan to submit the first paper of a (large) series on this in the next month or so.