Scientists May Have Detected The First Signature of a Black Hole's Event Horizon - ScienceAlert

Researchers report a subtle feature in the gravitational-wave signal from a merger of two massive black holes that may be the first direct signature of a black hole's event horizon. If real, the feature—seen during the ringdown phase—would support the picture that the remnant behaves like a classical black hole rather than an exotic compact object and would provide a strong-field test of general relativity. This event-level waveform detail complements population studies and could help connect individual merger physics to different black-hole formation channels.