Meet the parents: the progenitor binary for the supermassive black hole candidate in E1821+643

Abstract

The remnants of binary black hole mergers can be given recoil kick velocities up to $5,000\text{ km s$^{-1}$}$ due to anisotropic emission of gravitational waves. E1821+643 is a recoiling supermassive black hole moving at $\sim 2,100\text{ km s$^{-1}$}$ along the line-of-sight relative to its host galaxy. This suggests a recoil kick of $\sim 2,240\text{ km s$^{-1}$}$. Such a kick is powerful enough to eject E1821+643 from its $M_{\text{gal}}\sim 2\times 10^{12}{\text{ M}}_{\odot }$ host galaxy. In this work, we address the question: what are the likely properties of the progenitor binary that formed E1821+643? Using astrophysically motivated priors, we infer that E1821+643 was likely formed from a binary black hole system with masses of $m_1\sim 1.9_{-3.8}^{+5.0}\times 10^9{\text{ M}}_{\odot }$, $m_2\sim 8.1_{-3.2}^{+3.9}\times 10^8{\text{ M}}_{\odot }$ (90\% credible intervals). The black holes in this binary were likely to be spinning rapidly with dimensionless spin magnitudes of ${\chi }_1=0.87_{-0.26}^{+0.11}$, ${\chi }_2=0.77_{-0.37}^{+0.19}$. Such a high recoil velocity is impossible for spins aligned to the orbital angular momentum axis. This suggest that E1821+643 merged in hot gas, which is thought to provide an environment where spin alignment from accretion proceeds slowly relative to the merger timescale. We infer that E1821+643 is likely to be rapidly rotating with dimensionless spin $\chi =0.92\pm 0.04$. A $2.6\times 10^9{\text{ M}}_{\odot }$ black hole, recoiling from a gas-rich environment at $v\sim 2,240\text{ km s$^{-1}$}$ is likely to persist as an active galactic nuclei for $\sim 860$ Myr, in which time it traverses $\sim 2$ Mpc.

7 pages, 3 figures, 2 tables

References in corpus (17)

• Sub-milliarcsecond Imaging of Quasars and Active Galactic Nuclei III. Kinematics of Parsec-Scale Radio Jets
• The Population of Viscosity- and Gravitational Wave-Driven Supermassive Black Hole Binaries Among Luminous AGN
• Alignment of the spins of supermassive black holes prior to coalescence
• The Evolution of Black Hole Mass and Spin in Active Galactic Nuclei
• Ejection of Supermassive Black Holes from Galaxy Cores
• Getting a kick out of numerical relativity
• Fuelling Active Galactic Nuclei
• The host galaxies of luminous quasars
• Observable Signatures of a Black Hole Ejected by Gravitational Radiation Recoil in a Galaxy Merger
• Effects of gravitational-wave recoil on the dynamics and growth of supermassive black holes
• Interactions between multiple supermassive black holes in galactic nuclei: a solution to the final parsec problem
• Off-nuclear AGN as a signature of recoiling massive black holes
• Star Clusters Around Recoiled Black Holes in the Milky Way Halo
• Quasars with Periodic Variability: Capabilities and Limitations of Bayesian Searches for Supermassive Black Hole Binaries in Time-Domain Surveys
• SMILE: Search for MIlli-LEnses
• Periodicity in the continua and broad line curves of a quasar E1821+643
• The spatially offset quasar E1821+643: New evidence for gravitational recoil

Cited by in corpus (2)

• GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-Spin Black Hole Coalescence
• Astrophysical and relativistic modeling of the recoiling black-hole candidate in quasar 3C 186