Introducing EMP-Pathfinder: modelling the simultaneous formation and evolution of stellar clusters in their host galaxies

Abstract

The formation and evolution of stellar clusters is intimately linked to that of their host galaxies. To study this connection, we present the EMP-Pathfinder suite of cosmological zoom-in Milky Way-mass simulations. These simulations contain a sub-grid description for stellar cluster formation and evolution, allowing us to study the simultaneous formation and evolution of stellar clusters alongside their host galaxies across cosmic time. As a key ingredient in these simulations, we include the physics of the multi-phase nature of the interstellar medium (ISM), which enables studies of how the presence of a cold, dense ISM affects cluster formation and evolution. We consider two different star formation prescriptions: a constant star formation efficiency per free-fall time, as well as an environmentally-dependent, turbulence-based prescription. We identify two key results drawn from these simulations. Firstly, we find that tidal shock-driven disruption caused by the graininess of the cold ISM produces old (𝜏 > 10 Gyr) stellar cluster populations with properties that are in excellent agreement with the observed populations in the Milky Way and M31. Importantly, the addition of the cold ISM addresses the areas of disagreement found in previous simulations that lacked the cold gas phase. Secondly, the formation of stellar clusters is extremely sensitive to the baryonic physics that govern the properties of the cold, dense gas reservoir in the galaxy. This implies that the demographics of stellar cluster populations represent an important diagnostic tool for constraining baryonic physics models in upcoming galaxy formation simulations that also include a description of the cold ISM.

Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at $z>4$

“…Recent progress in modeling the formation of GCs has also been substantial, with a variety of approaches providing frameworks for understanding the formation of GCs both within their host galaxies and in the broader context of galaxy formation theory. Ongoing work on this front includes (1) simulations -at very high resolution but without a full cosmological context -of cluster formation within galaxies or molecular cloud complexes (He et al 2019;Li et al 2019;Lahén et al 2020;Lee et al 2021;Lahén et al 2021;Li et al 2021;Hislop et al 2022); (2) numerical or semi-numerical models of GC formation (which track GCs in cosmological context without directly resolving their formation; e.g., Katz & Ricotti 2014;Ricotti et al 2016;Li et al 2017;Renaud et al 2017;Pfeffer et al 2018;Creasey et al 2019;El-Badry et al 2019;Carlberg 2020;Halbesma et al 2020;Phipps et al 2020;Reina-Campos et al 2022);…”

In-situ or accreted? Using deep learning to infer the origin of extragalactic globular clusters from observables

“…We have also attempted to remove the underdisrupted GCs from the training and test samples. A new generation of simulations with better modelling of 𝐿 * galaxies and improved ISM physics will be needed to extend the origin predictions to metal-rich GCs with [Fe/H] > −0.5 (see Reina-Campos et al 2022), and will likely improve the identification of in-situ objects (see Sec. 5.1).…”

Formation and evolution of young massive clusters in galaxy mergers: the SMUGGLE view

“…Though huge efforts have been made in recent years (e.g. Li et al 2017Li et al , 2018Pfeffer et al 2018 ;Reina-Campos et al 2022 ), to quantitatively answer this question requires comprehensive modelling of the formation, orbital, and dynamical evolution of YMCs in hierarchical structure formation.…”