The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations

Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are important gravitational wave (GW) sources for the Laser Interferometer Space Antenna. It has recently been suggested that EMRIs and IMRIs can both form in the accretion disk of an active galactic nucleus (AGN). Co...

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Main Authors: Peng Peng, Alessia Franchini, Matteo Bonetti, Alberto Sesana, Xian Chen
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adef42
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author Peng Peng
Alessia Franchini
Matteo Bonetti
Alberto Sesana
Xian Chen
author_facet Peng Peng
Alessia Franchini
Matteo Bonetti
Alberto Sesana
Xian Chen
author_sort Peng Peng
collection DOAJ
description Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are important gravitational wave (GW) sources for the Laser Interferometer Space Antenna. It has recently been suggested that EMRIs and IMRIs can both form in the accretion disk of an active galactic nucleus (AGN). Considering the likely encounter between a stellar-mass black hole (sBH) and an intermediate-mass black hole (IMBH) during migration in the AGN disk, P. Peng & X. Chen (Paper I) showed that a gap-opening IMBH can drive a surrounding sBH to migrate synchronously. In this work, we extend the study in Paper I with a more sophisticated model. We first use 3D hydrodynamical simulations to study the coevolution of the disk and the migration of an sBH in the vicinity of an IMBH. We find that the gaseous torque, together with the tidal torque exerted by the IMBH, can drive synchronized migration until ∼10 Schwarzschild radii from the central supermassive black hole. We further use a relativistic three-body code to study the final fate of the sBH in the GW-dominated regime. We find that the sBH can be either captured or kicked out by the IMBH, which will result in either two subsequent IMRIs or an EMRI followed by an IMRI. These events will bring rich information about the formation and evolution of sBHs and IMBHs in AGNs.
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spelling doaj-art-095b3df5afd24bab8e96defc7e6ee3552025-08-20T03:41:08ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01989112210.3847/1538-4357/adef42The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body SimulationsPeng Peng0Alessia Franchini1https://orcid.org/0000-0002-8400-0969Matteo Bonetti2https://orcid.org/0000-0001-7889-6810Alberto Sesana3Xian Chen4https://orcid.org/0000-0003-3950-9317Astronomy Department, School of Physics, Peking University , 100871 Beijing, People’s Republic of China ; xian.chen@pku.edu.cnDepartment of Astrophysics, University of Zurich , Winterthurerstrasse 190, CH-8057 Zürich, SwitzerlandUniversità degli Studi di Milano-Bicocca , Piazza della Scienza 3, I-20126 Milano, Italy ; alberto.sesana@unimib.it; INFN , Sezione di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, ItalyUniversità degli Studi di Milano-Bicocca , Piazza della Scienza 3, I-20126 Milano, Italy ; alberto.sesana@unimib.it; INFN , Sezione di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, ItalyAstronomy Department, School of Physics, Peking University , 100871 Beijing, People’s Republic of China ; xian.chen@pku.edu.cn; Kavli Institute for Astronomy and Astrophysics at Peking University , 100871 Beijing, People’s Republic of ChinaExtreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are important gravitational wave (GW) sources for the Laser Interferometer Space Antenna. It has recently been suggested that EMRIs and IMRIs can both form in the accretion disk of an active galactic nucleus (AGN). Considering the likely encounter between a stellar-mass black hole (sBH) and an intermediate-mass black hole (IMBH) during migration in the AGN disk, P. Peng & X. Chen (Paper I) showed that a gap-opening IMBH can drive a surrounding sBH to migrate synchronously. In this work, we extend the study in Paper I with a more sophisticated model. We first use 3D hydrodynamical simulations to study the coevolution of the disk and the migration of an sBH in the vicinity of an IMBH. We find that the gaseous torque, together with the tidal torque exerted by the IMBH, can drive synchronized migration until ∼10 Schwarzschild radii from the central supermassive black hole. We further use a relativistic three-body code to study the final fate of the sBH in the GW-dominated regime. We find that the sBH can be either captured or kicked out by the IMBH, which will result in either two subsequent IMRIs or an EMRI followed by an IMRI. These events will bring rich information about the formation and evolution of sBHs and IMBHs in AGNs.https://doi.org/10.3847/1538-4357/adef42Active galactic nucleiIntermediate-mass black holesStellar mass black holesGravitational waves
spellingShingle Peng Peng
Alessia Franchini
Matteo Bonetti
Alberto Sesana
Xian Chen
The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
The Astrophysical Journal
Active galactic nuclei
Intermediate-mass black holes
Stellar mass black holes
Gravitational waves
title The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
title_full The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
title_fullStr The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
title_full_unstemmed The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
title_short The Fate of EMRI-IMRI Pairs in Active Galactic Nucleus Accretion Disks: Hydrodynamical and Three-body Simulations
title_sort fate of emri imri pairs in active galactic nucleus accretion disks hydrodynamical and three body simulations
topic Active galactic nuclei
Intermediate-mass black holes
Stellar mass black holes
Gravitational waves
url https://doi.org/10.3847/1538-4357/adef42
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