Small black holes could play 'hide-and-seek' with elusive supermassive black hole pairs 

 Small pairs of binary black holes could be used to play hide-and-seek' with elusive supermassive black hole binaries via gravitational waves carry the "baritone singing" of these cosmic titans. 

https://cdn.mos.cms.futurecdn.net/mVVgPwAMYPpsPtQzZN9rdA.png

https://www.space.com/black-holes-hide-and-seek-supermassive-binaries