While tens or hundreds of stellar-remnant black holes are expected to form in globular star clusters , it is still unclear how many of those will be retained upon formation , and how many will be ejected through subsequent dynamical interactions .
No such black holes have been found in any Milky Way globular cluster until the recent discovery of stellar-mass black holes in the globular cluster M 22 ( NGC 6656 ) with now an estimated population of 5 - 100 black holes .
We present a direct N -body model of a star cluster of the same absolute and dynamical age as M 22 .
Imposing an initial retention fraction of \approx 10 \% for black holes , 16 stellar-remnant black holes are retained at a cluster age of 12 Gyr , in agreement with the estimate for M 22 .
Of those 16 BHs , two are in a binary system with a main sequence star each while also one pure black hole binary is present .
We argue that multiple black holes can be present in any Milky Way cluster with an extended core radius , such as M 22 or the model presented here .