Merging black holes of any size and hierarchy

Giacomo Fragione*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


With the hundreds of merging binary black holes (BHs) expected to be detected by LIGO, LISA, and other upcoming instruments, the modelling of astrophysical channels that lead to the formation of compact BH binaries has become of crucial importance. BHs of any size can form bound systems in every astrophysical environment, from the field to galactic nuclei. If a binary is too wide, it needs a catalysis process to harden and merge, as in the case a third objects orbiting the BH binary on a distant orbit. In this case, Kozai-Lidov cycles can pump up the binary eccentricity, thus driving it to a merger thanks to efficient energy dissipation at the pericenter. Some remarkable scenarios where the Kozai-Lidov mechanism operates are in triple and quadruple systems of stellar BHs, and in intermediate-mass BH-stellar BH binaries in orbit around a central supermassive BH in galactic nuclei.

Original languageEnglish (US)
Pages (from-to)430-433
Number of pages4
JournalProceedings of the International Astronomical Union
Issue number351
StatePublished - 2019


  • Galaxy: centre
  • Galaxy: kinematics and dynamics
  • galaxies: star clusters: general
  • stars: black holes
  • stars: kinematics and dynamics
  • stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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