Hypercompact Stellar Systems Around Recoiling Supermassive Black Holes

Understand

A supermassive black hole ejected from the center of a galaxy by gravitational wave recoil carries a retinue of bound stars - a "hypercompact stellar system" (HCSS).

• The numbers and properties of HCSSs contain information about the merger histories of galaxies, the late evolution of binary black holes, and the distribution of gravitational-wave kicks.
• We relate the structural properties of HCSSs to the properties of their host galaxies, in two regimes: collisional, i.e.
• short nuclear relaxation times; and collisionless, i.e.