The Quiet Overtones of a Black Hole Are Now Heard Louder ⚡ экспресс
Gravitational-wave event GW250114 has the highest signal-to-noise ratio among those recorded to date. Previous analyses based on superpositions of quasinormal modes (QNMs) indicated the presence of the fundamental mode and the first overtone with l=m=2, but non-orthogonality of the modes introduced correlations that hindered confident isolation of subdominant components. In this work, an analysis with orthonormalized QNMs (arXiv:2507.12376) was applied: in a model including three modes with l=m=2 up to the second overtone, the significance of the first overtone increased from 82.5% to 99.9%. An assessment of deviations from the Kerr metric was also performed using the orthonormalized approach, and no significant discrepancies were found. The results demonstrate that orthonormalized QNMs provide more robust identification of weak modes in high-SNR signals, which is important for future gravitational-wave observations.
When two black holes merge, the resulting black hole 'rings' for a while, emitting gravitational waves — like a dying bell. This ringing is captured by giant detectors created by Rainer Weiss and Kip Thorne. Within the sound, you can distinguish the fundamental tone and overtones, which reveal the mass and spin of the black hole. But the quiet overtones usually get drowned out by the strong main signal.
Physicists found a way to isolate these faint notes, using spectroscopy — a method akin to fine-tuning an equalizer: it boosts the desired frequencies and suppresses noise. For the loudest recorded event, GW250114, they confirmed the first overtone with a confidence of 99.9% (previously 82.5%). No deviations from relativity — the black hole rang flawlessly.
Surprisingly, this quiet overtone told us as much about the black hole as the loud fundamental tone — we just hadn't heard it before. The cosmic eavesdropping session continues.
🎯 Every black hole rings with a unique set of frequencies, like a fingerprint, from which you can precisely determine its mass and spin.