2011ApJ...729L..25L

We present results of deep radio continuum observations of two galactic globular clusters 47 Tucanae (47 Tuc) and ω Centauri (ω Cen) with the Australia Telescope Compact Array. No statistically significant evidence for radio emission was found from the central region for the two clusters. However, both clusters show a 2.5σ detection near the center that may be confirmed by future deeper radio observations. The 3σ upper limits of the radio observations are 20 and 40 µJy/beam for ω Cen and 47 Tuc, respectively. By using the fundamental plane of accreting black holes, which describes the relationship between radio luminosity, X-ray luminosity, and black hole mass, we constrain the mass of a possible intermediate-mass black hole (IMBH) in the globualar clusters. We also compare our results with other globular clusters and discuss the existence of IMBHs in globular clusters.