This simulation shows a binary-binary encounter involving four black holes, which can occur at the cores of dense stellar systems such as gloublar clusters. Such encounters can lead to long-lived “resonating” interactions, through which many temporary binary systems are created. By incorporating a more accurate description of Einstein’s gravity in the equations of motion, the formation of a temporary, highly eccentric binary during the chaotic encounter can lead to a rapid inspiral and merge due to gravitational wave emission zapping orbital energy. These mergers can maintain their high eccentricies into the LIGO sensitive frequency range and occur at a rate accessible by Advanced LIGO/Virgo. If detected, such systems will highly constrain their formation scenario and be a clear indicator that dynamics can play a key role in facilitating binary black hole mergers.
To see the full paper, see https://arxiv.org/pdf/1810.00901.pdf. For more media, see https://michaelzevin.github.io/media/bbh_progenitors/.
Credit: Mike Zevin / Northwestern