Great Balls of FIRE II: The evolution and destruction of star clusters across cosmic time in a Milky Way-mass galaxy

Abstract

The current generation of galaxy simulations can resolve individual giant molecular clouds, the progenitors of dense star clusters. But the evolutionary fate of these young massive clusters (YMCs), and whether they can become the old globular clusters (GCs) observed in many galaxies, is determined by a complex interplay of internal dynamical processes and external galactic effects. We present the first star-by-star 𝑁-body models of massive (𝑁 ∼ 10 5 − 10 7 ) star clusters formed in a FIRE-2 MHD simulation of a Milky Way-mass galaxy, with all of the relevant initial conditions and galactic tidal effects extracted directly from the cosmological simulation. We randomly select 895 (∼ 30%) of the YMCs with > 6 × 10 4 𝑀 from Grudić et al. 2022 and integrate them to the present day using the Cluster Monte Carlo Code, CMC. This procedure predicts a MW-like system with 148 GCs, most of which were formed during the early, bursty mode of star formation in the galaxy. Our GCs are younger, less massive, and more core collapsed than clusters in the Milky Way or M31. This is a direct result of the assembly history and age-metallicity relationship of the GCs' host galaxy: younger clusters are preferentially born in stronger galactic tidal fields and initially retain fewer stellar-mass black holes, causing them to lose mass faster and reach core collapse sooner than their older counterparts. Our results suggest that the masses and core/half-light radii of GCs are shaped not only by internal dynamical processes, but by the specific evolutionary history of their host galaxies as well. These results emphasize that 𝑁-body studies with realistic stellar physics are crucial to understanding the evolution and present-day properties of galactic GC systems.

RELICS: Small-scale Star Formation in Lensed Galaxies at z = 6–10

“…Additional measurements of the stellar mass densities and circular velocities further support the interpretation of these as long-lived objects. Recent simulation results have also suggested external effects within their host galaxies (Rodriguez et al 2022), though we do not directly assess these effects here. Given the measured stellar mass of WHL 0137-zD1.1, coupled with the fact that it appears to be gravitationally bound, we conclude that this object is a YMC that will likely survive long-term, making it a proto-globular cluster candidate.…”

The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I

“…Fall & Zhang 2001), although it remains a challenge to model GCLFs in detail (e.g. Li & Gnedin 2019;Reina-Campos et al 2022;Rodriguez et al 2022). There are mild correlations observed of turnover magnitude 𝑀 0 and magnitude spread 𝜎 with host galaxy luminosity (e.g.…”

Impact of Radiation Feedback on the Formation of Globular Cluster Candidates during Cloud–Cloud Collisions

“…All quantities are measured inside a sphere of 2 pc radius from the cluster center. initial stellar mass due to stellar evolution, tidal disruption, and evaporation due to two-body relaxation, while their size increases by a factor of up to two (see also Larsen et al 2012;Madrid et al 2012;Kruijssen 2015;Rodriguez et al 2022). If these effects are considered, as shown by dashed boxes in Figure 7, it is possible that the simulated clusters evolve into normal present-day GCs.…”