> But there are also binary black holes. A binary black hole system will keep any other companions quite far from the binary, and perhaps not even allow compan

> But there are also binary black holes. A binary black hole system will keep any other companions quite far from the binary, and perhaps not even allow companions at any distance. What is the density of lone black holes and black hole binaries that we could have in -say- our galaxy before we would notice them frequently in the same way as in TFA? Well, presumably LIGO would sense them, or could if they knew what to look for.