Celebrating the 10th Anniversary of the First Gravitational Wave Detection

On September 14, 2015, the two LIGO detectors in the United States made the first-ever direct detection of gravitational waves (GW150914). These waves were generated by the merger of a binary black hole system, marking the beginning of a new era in astronomical observation.

Subsequently, in 2017, gravitational waves from the merger of binary neutron stars (GW170817) were detected. This event was accompanied by a gamma-ray burst and successful follow-up observations using electromagnetic telescopes, ushering in the era of multi-messenger astronomy, which combines gravitational wave and electromagnetic observations.

By January 2024, more than 200 gravitational wave events—primarily from binary black hole mergers—had been detected, demonstrating the rapid advancement of gravitational wave astronomy. These events are compiled in the GWTC-4.0 catalog released in August 2025 [1].

To commemorate the 10th anniversary of the first detection, the LIGO-Virgo-KAGRA collaboration announced the gravitational wave event GW250114, observed on January 14, 2025 [2]. This event, like GW150914, originated from a binary black hole merger with nearly identical mass, spin, and distance, but was detected with a signal strength approximately three to four times greater. This reflects the significant improvement in detector sensitivity since 2015. Furthermore, this clear signal has enabled the observational confirmation of the black hole area theorem proposed by Stephen Hawking with greater precision than ever before.

On the occasion of this 10th anniversary, Professor Takaaki Kajita, Distinguished Professor at the University of Tokyo and Principal Investigator of KAGRA, commented:

“Ten years have passed since the first detection of gravitational waves, and we now stand at a turning point in the remarkable growth of gravitational wave astronomy. As a later entrant to this field, KAGRA has received warm encouragement from many supporters. Thanks to these continued efforts and support, our detector sensitivity has significantly improved, bringing us ever closer to our first direct detection.

It is our strong belief that during the upcoming fifth international observation run, KAGRA will be able to make meaningful contributions to the advancement of gravitational wave astronomy.

We sincerely appreciate your continued support and encouragement.”

The fourth observation run of LIGO-Virgo-KAGRA is scheduled to continue until November 18, 2025. In 2026, a detailed announcement of gravitational wave events detected since 2024 is also planned.

We look forward to the continued development of gravitational wave astronomy.

[1] “GWTC-4.0 Catalog” page in “Gravitational Wave Science”(Link)

[2] “GW250114” page in “Gravitational Wave Science”(Link)