Interaction of Recoiling Supermassive Black Holes with Stars in Galactic Nuclei

TL;DR

This study uses large-scale simulations to explore how recoiling supermassive black holes interact with stars in galactic centers, revealing insights into tidal disruption rates and stellar environments post-merger.

Contribution

It provides the first detailed N-body simulation analysis of recoiling SMBHs and their stellar interactions, including tidal disruption rates and stellar environment characteristics.

Findings

Tidal disruption rates are about ten times lower than for stationary SMBHs.

Most stellar disruptions occur when SMBHs pass through the galactic center.

A bound star cluster and a cloud of unbound stars form around the oscillating SMBH.

Abstract

Supermassive black hole binaries (SMBHBs) are the products of frequent galaxy mergers. The coalescence of the SMBHBs is a distinct source of gravitational wave (GW) radiation. The detections of the strong GW radiation and their possible electromagnetic counterparts are essential. Numerical relativity suggests that the post-merger supermassive black hole (SMBH) gets a kick velocity up to 4000 km/s due to the anisotropic GW radiations. Here we investigate the dynamical co-evolution and interaction of the recoiling SMBHs and their galactic stellar environments with one million direct N-body simulations including the stellar tidal disruption by the recoiling SMBHs. Our results show that the accretion of disrupted stars does not significantly affect the SMBH dynamical evolution. We investigate the stellar tidal disruption rates as a function of the dynamical evolution of oscillating SMBHs in the galactic nuclei. Our simulations show that most of stellar tidal disruptions are contributed by the unbound stars and occur when the oscillating SMBHs pass through the galactic center. The averaged disruption rate is ~10^{-6} M_\odot yr^{-1}, which is about an order of magnitude lower than that by a stationary SMBH at similar galactic nuclei. Our results also show that a bound star cluster is around the oscillating SMBH of about ~ 0.7% the black hole mass. In addition, we discover a massive cloud of unbound stars following the oscillating SMBH. We also investigate the dependence of the results on the SMBH masses and density slopes of the galactic nuclei.