Resonant Dynamical Friction in Nuclear Star Clusters: Rapid Alignment of an Intermediate-mass Black Hole with a Stellar Disk
- 1 October 2021
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 919 (2), 140
- https://doi.org/10.3847/1538-4357/ac13ab
Abstract
We investigate the dynamical evolution of an intermediate-mass black hole (IMBH) in a nuclear star cluster hosting a supermassive black hole (SMBH) and both a spherical and a flattened disk-like distribution of stellar-mass objects. We use a direct N-body (phi GPU) and an orbit-averaged (N-ring) numerical integrator to simulate the orbital evolution of stars and the IMBH. We find that the IMBH's orbit gradually aligns with the stellar disk if their mutual initial inclination is less than 90 degrees. If it is larger than 90 degrees, i.e., counter-rotating, the IMBH does not align. Initially, the rate of orbital reorientation increases linearly with the ratio of the mass of the IMBH over the SMBH mass, and it is orders of magnitude faster than ordinary (i.e., Chandrasekhar) dynamical friction, particularly for high SMBH masses. The semimajor axes of the IMBH and the stars are approximately conserved. This suggests that the alignment is predominantly driven by orbit-averaged gravitational torques of the stars, a process that may be called resonant dynamical friction. The stellar disk is warped by the IMBH, and ultimately increases its thickness. This process may offer a test for the viability of IMBH candidates in the Galactic Center. Resonant dynamical friction is not limited to IMBHs; any object much more massive than disk particles may ultimately align with the disk. This may have implications for the formation and evolution of black hole disks in dense stellar systems and gravitational wave source populations for LIGO, VIRGO, KAGRA, and LISA.This publication has 126 references indexed in Scilit:
- SELF-PERPETUATING SPIRAL ARMS IN DISK GALAXIESThe Astrophysical Journal, 2013
- IS THERE AN INTERMEDIATE MASSIVE BLACK HOLE IN THE GALACTIC CENTER: IMPRINTS ON THE STELLAR TIDAL-DISRUPTION RATEThe Astrophysical Journal, 2012
- SECULAR DYNAMICAL ANTI-FRICTION IN GALACTIC NUCLEIThe Astrophysical Journal, 2012
- INTERACTION OF RECOILING SUPERMASSIVE BLACK HOLES WITH STARS IN GALACTIC NUCLEIThe Astrophysical Journal, 2012
- THE TORQUING OF CIRCUMNUCLEAR ACCRETION DISKS BY STARS AND THE EVOLUTION OF MASSIVE BLACK HOLESThe Astrophysical Journal, 2012
- A DISK OF YOUNG STARS AT THE GALACTIC CENTER AS DETERMINED BY INDIVIDUAL STELLAR ORBITSThe Astrophysical Journal, 2008
- The Ecology of Star Clusters and Intermediate‐Mass Black Holes in the Galactic BulgeThe Astrophysical Journal, 2006
- The Need for a Second Black Hole at the Galactic CenterThe Astrophysical Journal, 2003
- The influence of the Galactic tidal field on the Oort comet cloudIcarus, 1986
- The formation of the nuclei of galaxies. I - M31The Astrophysical Journal, 1975