No Evidence for Intermediate-Mass Black Holes in Globular Clusters: Strong Constraints from the JVLA

Understand

With a goal of searching for accreting intermediate-mass black holes (IMBHs), we report the results of ultra-deep Jansky VLA radio continuum observations of the cores of three Galactic globular clusters: M15, M19, and M22.

• We reach rms noise levels of 1.5-2.1 uJy/beam at an average frequency of 6 GHz.
• No sources are observed at the center of any of the clusters.
• For a conservative set of assumptions about the properties of the accretion, we set 3-sigma upper limits on IMBHs from 360-980 M_sun.