Analyses of the spin and mass asymmetry show that in each case the larger black hole both significantly outweighs its companion and shows a spin configuration that deviates from expectations for first-generation stellar-collapse black holes. These features suggest that at least one of the two black holes may be the product of a previous merger — a so-called second-generation black hole.

If confirmed, these findings would represent the first direct observation of hierarchical black-hole mergers. The detections provide new insights into the formation and evolution of black holes in dense astrophysical environments and open a new window for testing gravitational physics.

“GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-Spin Black Hole Coalescences” was published Oct. 28th in The Astrophysical Journal Letters