Eccentric

Routing (electronic design automation)

Quantum mechanics

Spin (aerodynamics)

Demography

Engineering

Orbit (dynamics)

Tilt (camera)

Aerospace engineering

Galaxy

Astrophysics

Computer science

Classical mechanics

Intermediate-mass black hole

Computer network

Binary black hole

Thermodynamics

Routing protocol

Physics

Mathematics

Active galactic nucleus

Astronomy

Angular momentum

Link-state routing protocol

Population

Sociology

Gravitational wave

Geometry

Black hole (networking)

Accretion (finance)

Spin-flip

Circular orbit

Nature

There is some weak evidence that the black hole merger named GW190521 had a non-zero eccentricity1,2. In addition, the masses of the component black holes exceeded the limit predicted by stellar evolution3. The large masses can be explained by successive mergers4,5, which may be efficient in gas disks surrounding active galactic nuclei, but it is difficult to maintain an eccentric orbit all the way to the merger, as basic physics would argue for circularization6. Here we show that active galactic nuclei disk environments can lead to an excess of eccentric mergers, if the interactions between single and binary black holes are frequent5 and occur with mutual inclinations of less than a few degrees. We further illustrate that this eccentric population has a different distribution of the inclination between the spin vectors of the black holes and their orbital angular momentum at merger7, referred to as the spin-orbit tilt, compared with the remaining circular mergers.

AGN as potential factories for eccentric black hole mergers