Title: Prospects for detection of intermediate-mass black holes in globular clusters using integrated-light spectroscopy,
Abstract: The detection of intermediate mass black holes (IMBHs) in Galactic globular
clusters (GCs) has so far been controversial. In order to characterize the
effectiveness of integrated-light spectroscopy through integral field units, we
analyze realistic mock data generated from state-of-the-art Monte Carlo
simulations of GCs with a central IMBH, considering different setups and
conditions varying IMBH mass, cluster distance, and accuracy in determination
of the center. The mock observations are modeled with isotropic Jeans models to
assess the success rate in identifying the IMBH presence, which we find to be
primarily dependent on IMBH mass. However, even for a IMBH of considerable mass
(3% of the total GC mass), the analysis does not yield conclusive results in 1
out of 5 cases, because of shot noise due to bright stars close to the IMBH
line-of-sight. This stochastic variability in the modeling outcome grows with
decreasing BH mass, with approximately 3 failures out of 4 for IMBHs with 0.1%
of total GC mass. Finally, we find that our analysis is generally unable to
exclude at 68% confidence an IMBH with mass of $10^3~M_\odot$ in snapshots
without a central BH. Interestingly, our results are not sensitive to GC
distance within 5-20 kpc, nor to mis-identification of the GC center by less
than 2'' (<20% of the core radius). These findings highlight the value of
ground-based integral field spectroscopy for large GC surveys, where systematic
failures can be accounted for, but stress the importance of discrete kinematic
measurements that are less affected by stochasticity induced by bright stars.