Star clusters around recoiled black holes in the Milky Way halo

摘要: Gravitational wave emission by coalescing black holes (BHs) kicks the remnant BH with a typical velocity of hundreds km s -1 . This is sufficiently large to remove from low-mass galaxy but below escape Milky Way (MW) galaxy. If central BHs were common in galactic building blocks that merged make MW, then numerous kicked out galaxies should be freely floating MW halo today. We use statistical sample possible merger tree histories for estimate expected number recoiled remnants present find remain bound after leaving their parent galaxies. Each carries compact cluster old stars populated core its original host Using time-dependent Fokker-Planck equation, we present-day clusters are ≤ 1 pc size, and bright regions unresolved most existing sky surveys. These systems distinguishable globular internal (Keplerian) dispersion greater than 100 high mass-to-light ratio owing BH. An observational discovery this relic population star would constrain formation history dynamics mergers early Universe. A similar exist around other may potentially detectable M31 M33.