What lurks in the cores of globular clusters: white dwarfs, black holes or nothing?

What lurks in the cores of globular clusters: white dwarfs, black holes (stellar or intermediate) or nothing?
Presenter: Prof. Dr. Gary Mamon (Institut d’astrophysique de Paris, FR)


Globular clusters (GCs) represent unique laboratories for collisional dynamics, because contrary to galaxies, dynamical interactions between stars are not negligible. The inner regions of GCs are full of mysteries: could the high density of stars in the 20% of GCs with cuspy stellar surface density profiles lead to the hotly debated intermediate-mass black holes? I will present work performed with my Brazilian doctoral student, Eduardo Vitral, where we used my MAMPOSSt-PM bayesian mass-orbit modeling code to analyze the internal kinematics of several GCs, using the proper motions of their stars measured by HST and Gaia. We find that the GCs all have inner mass excesses, but with diverse conclusions on their main constituents, highlighting the usefulness of combining this mass analysis with N-body-like simulations. I will finish by presenting an idea for better astrometric observations after Gaia.


Gary Mamon is a senior astronomer at Institut d’Astrophysique de Paris [IAP] (Sorbonne Université & CNRS). He returned to France after a PhD at Princeton and a postdoc at NYU, first at Observatoire de Meudon, then at IAP since 1993. He specializes in kinematic and dynamical modeling, groups and clusters of galaxies, as well as galaxy formation and evolution, and recently in epidemiology.

Gary Mamon
Senior Astronomer
Institut d’Astrophysique de Paris (IAP)
[CNRS & Sorbonne Université]
98 bis Bd Arago
F-75014 Paris, FRANCE
+33 (0) 1 4432-8115

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