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

TL;DR

This paper uses the GW250114 gravitational-wave event to place the strongest observational constraints on black hole tidal Love numbers, supporting the prediction that they are zero in classical general relativity.

Contribution

It provides the first tight upper limits on black hole tidal deformability from gravitational-wave data, testing fundamental physics predictions.

Findings

Consistent with Kerr black holes having zero tidal Love numbers.

Placed a 90% upper limit of 34.8 on effective tidal deformability.

Ruling out some models of exotic compact objects.

Abstract

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 $\tilde{\Lambda} < 34.8$. 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.