2025/11/13
GW250114: The Strongest Gravitational Wave Signal Ever Detected
On January 14, 2025, the two LIGO detectors observed GW250114, the strongest gravitational wave signal ever recorded. This signal was produced by the merger of two black holes, and its signal-to-noise ratio (SNR) reached approximately 80. That is three to four times stronger than the previous strongest signals, making this observation extremely valuable for gravitational wave research.
What Kind of Black Holes Merged?
GW250114 is believed to have originated from the merger of two black holes, with masses of approximately 34 and 32 times the mass of the Sun. Their collision formed a larger black hole and released powerful gravitational waves that traveled across the universe to Earth.
What Did Scientists Learn?
Thanks to the exceptional strength of this signal, scientists were able to investigate several key aspects in detail:
- Black Hole Vibrations: By analyzing the vibrations of the newly formed black hole—known as quasi-normal modes—researchers measured the frequencies and damping rates of multiple vibration modes. This kind of study is called black hole spectroscopy, which helps reveal the nature of black holes.
- Testing Black Hole Properties: The measurements of these vibration modes confirmed that the final black hole behaves like a Kerr black hole, as predicted by Einstein’s general relativity. No significant deviations were found.
- Verifying Hawking’s Area Theorem: Scientists tested the black hole area theorem, which states that the total surface area of the event horizons should not decrease after a merger. The results showed, with greater precision than before, that the area of the final black hole’s event horizon was indeed larger than the combined areas of the two original black holes, consistent with the theory.
Why Is This Event Important?
GW250114 is significant because a single event provided more precise tests of gravitational theories than many previous detections combined. It allowed scientists to study black hole’s behavior and the nature of gravity in greater detail than ever before, marking a major milestone in the advancement of gravitational wave astronomy.
Gravitational wave signals like GW250114 allow us to “listen” to the universe’s most extreme phenomena and test the limits of our physical laws. Thanks to the international collaboration between LIGO, Virgo, and KAGRA, we are steadily uncovering the deep mysteries of the cosmos.
Glossary
Quasi-Normal Modes of Black Holes
Just as a drum produces characteristic tones, a black hole undergoes damped oscillations at specific frequencies and decay rates determined by its mass and spin angular momentum. These oscillations are known as the quasi-normal modes of a black hole. There are multiple combinations of frequencies and decay rates, each referred to as a quasi-normal mode.
When two black holes merge to form a single black hole, these quasi-normal modes are excited immediately after the merger. The resulting gravitational waves carry information about these vibrations and have been observed by detectors.
Hawking’s Area Theorem
The area theorem, proposed by Stephen Hawking in 1971, is a result of general relativity stating that the surface area of a black hole’s event horizon can never decrease. According to this theorem, when two black holes merge into one, the surface area of the resulting black hole’s event horizon must be greater than or equal to the sum of the areas of the two original black holes’ horizons.nal-wave-astronomy/
Papers
Discovery:
https://arxiv.org/abs/2509.08054
https://journals.aps.org/prl/abstract/10.1103/kw5g-d732
BH spectroscopy and TGR:
https://arxiv.org/abs/2509.08099
Science Summary
Discovery:
https://ligo.org/science-summaries/GW250114_discovery/
https://ligo.org/wp-content/uploads/2025/09/GW250114_discovery.pdf
BH spectroscopy and TGR:
https://ligo.org/science-summaries/GW250114_TGR/
https://ligo.org/wp-content/uploads/2025/09/GW250114_TGR.pdf
Other languages: https://ligo.org/science-summaries/
Announcement by LIGO
https://ligo.org/detections/gw250114-10-years-of-gravitational-wave-astronomy/