2026-08-24 カリフォルニア大学サンタバーバラ校（UCSB）
Photo Credit:NASA, ESA, Leah Hustak (STScI)
The rogue super-massive black hole compresses gas in its wake, forming a long “contrail” of young, blue stars. This unusual event happened when the universe was approximately half its current age.
＜関連情報＞
- https://news.ucsb.edu/2026/022754/physicists-reconstruct-collision-launched-runaway-black-hole
- https://journals.aps.org/prl/abstract/10.1103/fm3n-sy3f
Progenitor of the Recoiling Supermassive Black Hole RBH-1 Identified Using HST and JWST Imaging
Tousif Islam, Tejaswi Venumadhav, and Digvijay Wadekar
Physical Review Letters Published: 17 July, 2026
DOI: https://doi.org/10.1103/fm3n-sy3f
Abstract
Using a combination of Hubble Space Telescope and James Webb Space Telescope imaging, a runaway supermassive black hole was recently identified with an inferred velocity of 954+110−126 km s−1, likely ejected from a compact star-forming galaxy at z≈0.96. Assuming the runaway black hole originated from a gravitational-wave-driven merger of two supermassive black holes (SMBHs), we combine its measured recoil velocity with gravitational-wave recoil predictions from numerical relativity and black-hole perturbation theory to constrain the mass ratio and spin configuration of the progenitor binary that overcame the final-parsec problem and merged ∼70 Myr ago. We find that the progenitor binary must have been precessing, with a mass ratio m1/m2 ≲6, and that the more massive SMBH likely possessed a high dimensionless spin magnitude ( ∼0.75) in order to generate a recoil of this magnitude. Such SMBH mergers could represent an interesting source population for the upcoming Laser Interferometer Space Antenna mission, with characteristic signal-to-noise ratios of order ≳103. Furthermore, the inferred progenitor SMBH properties suggest that the compact galaxy likely originated from a major, gas-rich (“wet”) merger between two galaxies of comparable mass, with a mass ratio ≲4.
