The formation of mini-AGN disks around IMBHs and their dynamical implications

TL;DR

This paper investigates the formation, stability, and observable consequences of mini-AGN disks around intermediate-mass black holes in globular clusters, highlighting their role in gravitational wave events and electromagnetic signatures.

Contribution

It introduces a comprehensive analysis of mAGN disk formation around IMBHs, modeling their dynamics and potential observational phenomena, which is novel in connecting disk physics with gravitational wave and electromagnetic signals.

Findings

Gas hardening accelerates binary inspirals within the disk.

Potential formation of ultraluminous X-ray sources from captured binaries.

Observable signatures include unique gravitational wave and electromagnetic signals.

Abstract

This study explores the formation and implications of mini-active galactic nuclei (mAGN) disks around intermediate-mass black holes (IMBHs) embedded in gas-rich globular/nuclear clusters (GCs). We examine the parameter space for stable mAGN disks, considering the influence of IMBH mass, disk radius, and gas density on disk stability. The dynamics of stars and black holes within the mAGN disk are modeled, with a focus on gas-induced migration and gas dynamical friction. These dynamical processes can lead to several potentially observable phenomena, including the alignment of stellar orbits into the disk plane, the enhancement of gravitational wave mergers (particularly IMRIs and EMRIs), and the occurrence of mili/centi-tidal disruption events (mTDEs/cTDEs) with unique observational signatures. We find that gas hardening can significantly accelerate the inspiral of binaries within the disk, potentially leading to a frequency shift in the emitted gravitational waves. Additionally, we explore the possibility of forming accreting IMBH systems from captured binaries within the mAGN disk, potentially resulting in the formation of ultraluminous X-ray sources (ULXs). The observational implications of such accreting systems, including X-ray emission, optical signatures, and transient phenomena, are discussed. Furthermore, we investigate the possibility of large-scale jets emanating from gas-embedded IMBHs in GCs. While several caveats and uncertainties exist, our work highlights the potential for mAGN disks to provide unique insights into IMBH demographics, accretion physics, and the dynamics of GCs.