Black Holes in Globular Clusters
Vincent Henault-Brunet
St. Mary's University

Globular clusters (GCs) are among the oldest stellar systems in the Universe and may be the surviving counterparts of the compact, dense star-forming clumps now observed at high redshift with JWST, with initial densities reaching up to about a million solar masses per cubic parsec. Such initial conditions are expected to produce large populations of tightly packed stellar remnants in cluster cores, including black holes (BHs), which play a central role in cluster dynamical evolution and are now recognized as important contributors to gravitational-wave sources detected by LIGO-Virgo-KAGRA. In addition, dense GCs provide possible environments for the formation of intermediate-mass black holes (IMBHs) and exotic transients such as fast radio bursts. The presence of BHs in GCs also has a significant impact on the properties of stellar streams formed from dissolving clusters and used to probe dark matter. However, major uncertainties remain regarding the initial conditions of GCs, BH natal kicks, and the retention and demographics of their BH populations at the present day. In this talk, I will present our recent work aimed at rewinding the dynamical evolution of Milky Way GCs to address open questions about the formation and evolution of these systems. Using a combination of multimass dynamical modelling and a fast cluster evolution code, we model GCs by fitting a wide range of observations (spatial distribution of stars, kinematics, pulsar timing) as boundary conditions for the long-term evolution of clusters and their BH populations. I will show evidence that GCs formed with a bottom-light initial stellar mass function (IMF), implying enhanced production of massive remnants compared to the commonly assumed IMF. I will then discuss constraints on present-day BH populations across a large sample of clusters, and how these results inform both their early densities and the magnitude of BH natal kicks. I will present new modelling of the orbits of fast-moving stars in Omega Centauri, supporting the presence of an IMBH and enabling predictions for future observational tests, as well as new stringent upper limits on the central dark mass of other massive GCs based on pulsar timing. Together, these results connect present-day observables to the early evolution of GCs and provide new insight into the formation and role of BHs in dense stellar systems.

Date:	Mardi, le 5 mai 2026
Heure:	15:30
Lieu:	Université McGill
	Ernest Rutherford Physics, R.E. Bell Conference Room (room 103)