In the presence of an ultralight scalar or vector boson, a spinning black hole will be spun down through the superradiant instability. We use spin measurements from gravitational wave observations of binary black holes, in particular the heavy binary black hole merger event GW231123, along with the lower-mass GW190517 event, to constrain the existence of ultralight bosons. We disfavor scalars with masses in the range of [0.55,11]×10−13 eV and vectors in the range of [0.11,18]×10−13 eV, making only a conservative assumption that the black hole lifetimes are greater than 105 years. The lower ends of these ranges, where the exclusion confidence is the highest, were not previously excluded by spin measurements from electromagnetic or gravitational wave observations. We map these constraints to axion and dark photon models with interactions.
@article{arxiv.2507.20979,
title = {Ultralight boson constraints from gravitational wave observations of spinning binary black holes},
author = {P. S. Aswathi and William E. East and Nils Siemonsen and Ling Sun and Dana Jones},
journal= {arXiv preprint arXiv:2507.20979},
year = {2026}
}