No Love for black holes: tightest constraints on tidal Love numbers of black holes from GW250114

Tidal Love numbers of black holes, zero in classical general relativity for Kerr black holes in vacuum, become non-vanishing in the presence of exotic matter or in alternative theories of gravity, making them a powerful probe of fundamental physics. The gravitational-wave event GW250114, observed with an unprecedented signal-to-noise ratio, provides a unique opportunity to test this prediction. By analyzing this event, we conclude that the data is consistent with the binary black hole hypothesis, and we place a 90% upper limit on the effective tidal deformability of $\tilde{\mathrm{\Lambda }}<34.8$. These bounds imply that any environment surrounding the black holes must contribute less than $\sim 7\times {10}^{-3}$ of their mass, and they rule out some models of boson stars. Our findings provide the strongest observational constraints yet on black hole tidal deformability and show that the data remain fully consistent with the Kerr black hole prediction of vanishing tidal Love numbers.