Lessons learned from GW250114: a loud signal with no Love

Giada Santoro examines strong-field gravity and compact-object structure using GW250114, a gravitational-wave event with signal-to-noise ratio around eighty. The unusually strong signal supports precise tests of departures from general relativity and detailed measurements of black-hole ringdown. No tidal deformability is detected: the analysis places a ninety-percent upper bound of 34.8 on the effective tidal-deformability parameter. This is consistent with the vanishing tidal response predicted for Kerr black holes.