Core radii of globular clusters in the Large and Small Magellanic Clouds show an increasing trend with age. We propose that this trend is a dynamical effect resulting from the accumulation of massive stars and stellarmass black holes at the cluster centers. The black holes are remnants of stars with initial masses exceeding ∼ 20 - 25M⊙; as their orbits decay by dynamical friction, they heat the stellar background and create a core. Using analytical estimates and N-body experiments, we show that the sizes of the cores so produced and their growth rates are consistent with what is observed. We propose that this mechanism is responsible for the formation of cores in all globular clusters and possibly in other systems as well (Refer to PDF file for exact formulas).

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© 2004. The American Astronomical Society. All rights reserved. Printed in U.S.A.

This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1086/422252

Supported by NSF grant AST02-0631, NASA grant NAG5-9046, and grant HST-AR-09519.01-A from STScI. SPZ was supported by the Royal Netherlands Academy of Sciences (KNAW), the Dutch Organization of Science (NWO), and by the Netherlands Research School for Astronomy (NOVA).

Also archived in: arXiv:astro-ph/0403331 v2 17 Mar 2004

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Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus