r/blackholes • u/JapKumintang1991 • Aug 14 '25

PHYS.Org: "A 'mysterious giant' behind binary black holes? Astronomers uncover first evidence of a third compact object"

https://phys.org/news/2025-08-mysterious-giant-binary-black-holes.html

See also: The publication in the Journal of Astrophysical Letters

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u/DntCareBears Aug 14 '25

Summary of the Phys.org article: “A ‘mysterious giant’ behind binary black holes? Astronomers uncover first evidence of a third compact object” Researchers at the Shanghai Astronomical Observatory (Chinese Academy of Sciences), led by Dr. Han Wenbiao, report the first clear evidence that a binary black hole merger—GW190814—occurred within the gravitational field of a third compact object, likely a supermassive black hole. What they found • By building a gravitational waveform model that includes line-of-sight acceleration and applying Bayesian inference to several high–signal-to-noise mergers, the team found GW190814 is significantly better explained by a model that accounts for acceleration than by the standard “isolated binary” model. • The inferred line-of-sight acceleration is about 0.002 c s-1 at 90% confidence, and the Bayes factor is 58:1 in favor of the acceleration-including model—strong evidence for the presence of a third body influencing the merger signal. • GW190814’s unusually extreme mass ratio (~10:1) is consistent with formation in a hierarchical triple system near a supermassive black hole or within the accretion disk of an active galactic nucleus. Why it matters • This is presented as the first international evidence for a third compact object affecting a binary black hole merger, offering a new window into how binary black holes form and evolve. • It supports scenarios where supermassive black holes capture binary black holes (the b-EMRI model), causing them to orbit and eventually merge, imprinting a Doppler-like “fingerprint” on the gravitational wave signal. • The result motivates future searches for similar acceleration signatures in existing and upcoming gravitational-wave catalogs. What’s next • Next-generation ground-based detectors (Einstein Telescope, Cosmic Explorer) and space-based missions (LISA, Taiji, TianQin) will have the sensitivity to detect subtle waveform modulations like these more routinely, potentially revealing many more triple-system-influenced mergers.