GW250114 reveals signatures of post-merger black-hole horizon

Oshita, N., Ma, S., Chen, Y. & Yang, H. Probing direct waves in black hole ringdowns. Preprint at https://arxiv.org/abs/2509.09165 (2025). Abac, A. G. et al. GW250114: testing Hawking’s area law and the Kerr nature of black holes. Phys. Rev. Lett. 135 , 111403 (2025). Article ADS CAS PubMed Google Scholar Akiyama, K. et al. First M87 Event Horizon Telescope results. I. The shadow of the supermassive black hole. Astrophys. J. Lett. 875 , L1 (2019). Article ADS CAS Google Scholar Reynolds, C. S. Measuring black hole spin using X-ray reflection spectroscopy. Space Sci. Rev. 183 , 277–294 (2014). Article ADS Google Scholar Blandford, R. D. & Znajek, R. L. Electromagnetic extraction of energy from Kerr black holes. Mon. Not. R. Astron. Soc. 179 , 433–456 (1977). Article ADS Google Scholar Aasi, J. et al. Advanced LIGO. Class. Quantum Gravity 32 , 074001 (2015). Article ADS Google Scholar Acernese, F. et al. Advanced Virgo: a second-generation interferometric gravitational wave detector. Class. Quantum Gravity 32 , 024001 (2014). Article ADS Google Scholar Akutsu, T. et al. Overview of KAGRA: detector design and construction history. Prog. Theor. Exp. Phys. 2021 , 05A101 (2020). Article Google Scholar The LIGO Scientific Collaboration, the Virgo Collaboration & the KAGRA Collaboration. GWTC-4.0: updating the gravitational-wave transient catalog with observations from the first part of the fourth LIGO–Virgo–KAGRA observing run. Preprint at https://arxiv.org/abs/2508.18082 (2025). …