Presentation #535.20 in the session “New Views of Galaxy Formation and Evolution”.
Intermediate-mass black holes (IMBHs) are defined as having masses of about 102 to 105 Msun, a range poorly explored observationally. Finding IMBHs in present-day globular star clusters (GCs) would validate a formation channel for seed black holes in the early universe. Examining a large number of GCs per galaxy is key, as dynamical models predict that only a few percent overall will retain their putative IMBHs against gravitational wave recoils. Here, we simulate an ngVLA observation of 670 GCs in M49, the brightest galaxy in the Virgo Cluster. We describe how to convert an ngVLA signal from each GC to an IMBH mass, using semi-empirical accretion models. We find that for a given sensitivity, detecting accretion signatures from IMBHs in the GCs is easier if the accretion is fed by adiabatic flows, and harder if fed by isothermal flows. At the anticipated temperatures of about 104 K, the cooling function suggests that the flows will be isothermal. We also explore potential outcomes from a stacking analysis of the 670 GCs in M49. The NRAO is a facility of the NSF, operated under cooperative agreement by AUI. The ngVLA is a design and development project of the NSF operated under cooperative agreement by AUI.