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AGN as potential factories for eccentric black hole mergers
J Samsing1, I Bartos2, D J D'Orazio3
1Niels Bohr International Academy, Niels Bohr Institute, Copenhagen, Denmark. jsamsing@gmail.com.
Nature
|March 10, 2022
Summary
Active galactic nuclei disks can explain eccentric black hole mergers, challenging previous circularization theories. This finding impacts our understanding of black hole populations and their formation.
Area of Science:
- Astrophysics
- Gravitational Wave Astronomy
Background:
- The black hole merger GW190521 exhibited weak evidence of non-zero eccentricity and component black hole masses exceeding stellar evolution limits.
- Large black hole masses suggest successive mergers, potentially efficient in active galactic nuclei (AGN) disks, but maintaining eccentricity to merger is theoretically challenging due to circularization.
Purpose of the Study:
- To investigate how active galactic nuclei (AGN) disk environments can lead to an excess of eccentric black hole mergers.
- To explore the conditions under which eccentric mergers can form and their implications for black hole populations.
Main Methods:
- Simulations of black hole interactions within AGN disk environments.
- Analysis of merger dynamics considering single and binary black hole interactions with specific mutual inclinations.
Main Results:
- Active galactic nuclei (AGN) disk environments can produce an excess of eccentric mergers when interactions between single and binary black holes are frequent and occur with small mutual inclinations (< a few degrees).
- This population of eccentric mergers exhibits a distinct distribution of the spin-orbit tilt compared to circular mergers.
Conclusions:
- Active galactic nuclei (AGN) disks provide a viable environment for forming eccentric black hole mergers.
- The spin-orbit tilt distribution offers a potential observational signature to distinguish between eccentric and circular merger populations, aiding in understanding black hole formation pathways.
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