Three-body encounters in black hole discs around a supermassive black hole: The disc velocity dispersion and the Keplerian tidal field determine the eccentricity and spin-orbit alignment of gravitational wave mergers

Understand

Dynamical encounters of stellar-mass black holes (BHs) in a disc of compact objects around a supermassive BH (SMBH) can accelerate the formation and coalescence of BH binaries.

• It has been proposed that binary-single encounters among BHs in such discs can lead to an excess of highly-eccentric BH mergers.
• However, previous studies have neglected how the disc velocity dispersion and the SMBH's tidal field affect the 3-body dynamics.
• We investigate the outcomes of binary-single encounters considering different values of the disc velocity dispersion, and examine the role of the SMBH's tidal field.