Principal Investigator: Laura Watkins
PI Institution: Space Telescope Science Institute - ESA - JWST
Title: Finding needles in haystacks: intermediate-mass black holes in Galactic globular clusters
We propose to improve the performance of existing dynamical-modelling tools, and then to use them to place limits on intermediate-mass black hole (IMBH) masses in a set of Galactic globular clusters. The existence of IMBHs is a topic with high astrophysical impact, however all reported detections so far have been disputed as neither data nor models have been sensitive enough to draw firm conclusions. Globular clusters are prime host candidates; to detect IMBHs in their crowded central regions requires extremely precise proper-motion measurements. This is only possible with the exquisite astrometric accuracy of HST. We have high-precision HST proper-motions for a set of Galactic globular clusters. These exceptional datasets have the potential to definitively address the issue of IMBHs, however, no existing modelling tools match their quality. Only with the modelling improvements we propose here will we correct that imbalance and make IMBH detection possible. This work is critical to maximise the potential of the HST datasets. We will generate mock datasets from N-body simulations of globular clusters and use them to improve the sensitivity of existing discrete dynamical models to the kinematic signals from IMBHs. With the tailored models, we will then investigate whether a mass-segregated population of stellar remnants may masquerade as an IMBH. Finally, we will apply the models to our existing HST proper motion datasets for a set of Galactic globular clusters to measure IMBH masses. The theoretical phase of the project is vital for the success of the subsequent data analysis, and will serve as a benchmark for future observational campaigns with HST, JWST and beyond.