Constraints on massive black holes as dark matter candidates using Galactic globular clusters

This work considers the idea of massive black holes being the constituents ofthe Galactic dark matter halo. It constrains the maximum black hole mass to$\mbh \sil 5 \times 10^4 \msun$ by examining their influence on the populationof globular clusters in our Milky Way. In the adopted halo model, globularclusters are exposed to constant bombardment of halo objects on their orbitsthrough the Galaxy and thus will steadily gain internal energy. Depending onthe mass of these halo objects and the structural parameters of the globularclusters, they can be disrupted on time scales of a few billion years andbelow. These disruption time scales are calculated using a modification of thewell known (classical) impulsive approximation and compared with direct N-bodysimulations of such encounter events to ensure the method works correctly. Fora set of ten prototypical globular cluster models and black hole masses rangingfrom $10^3$ to $10^7\:\msun$, Monte-Carlo-simulations of $10\,000$ encounterhistories over the period of 10 billion years were calculated each, at threedifferent galactocentric distances \mbox{$R = 5$}, $10$ and $15\, \kpc$. Thesedata were compared with the real globular cluster population in our Galaxy andused to obtain the above constraint of $\mbh \sil 5 \times 10^4 \msun$.