Formation and Evolution of Compact Objects in Active Galactic Nuclei

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• Tagawa Hiromichi, Tohoku University
• Wednesday 10 March 2021, 11:00-12:00
• online .

If you have a question about this talk, please contact Silvia Toonen.

The astrophysical origin of gravitational wave (GW) events discovered by LIGO /VIRGO remains an outstanding puzzle. The recently discovered gravitational wave sources GW190521 and GW190814 have shown evidence of BH mergers with masses and spins outside of the range expected from isolated stellar evolution. These merging objects could have experienced previous mergers. Such hierarchical mergers are predicted to be frequent in active galactic nuclei (AGN) disks, where binaries form and evolve efficiently by dynamical interactions and gaseous dissipation. We compared the properties of these observed events to the theoretical models of mergers in AGN disks, which are obtained by performing one-dimensional N-body simulations combined with semi-analytical prescriptions. I will discuss properties of mergers and promising signatures for this channel, which include high-BH masses due to repeated mergers, high eccentricities, and a significant Doppler drift of GWs. Also, I present that binaries formed in AGN disks can reproduce the distribution of low-mass X-ray binaries in the Galactic center, including an outer cutoff at ∼1 pc due to the competition between migration and hardening by gas torques

This talk is part of the Astrophysics Seminars series.

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