Black Hole Spectroscopy and Tests of General Relativity with GW250114

Using the exceptionally loud BBH event GW250114, the LVK Collaboration performs detailed inspiral–merger–ringdown tests of GR and black-hole spectroscopy of the remnant. The post-merger signal supports at least two quasi-normal modes, and the dominant mode and overtone are found consistent with Kerr predictions at the tens-of-percent level when analyzed at multiple post-peak times. A parameterized IMR analysis also constrains higher modes and bounds deviations of ringdown frequencies to the percent level, yielding single-event constraints comparable to—or stronger than—combined constraints from many O4 catalog events.

arXiv (gr-qc:2509.08099)