KAGRA: 2.5 generation interferometric gravitational wave detector

KAGRA collaboration

Research output: Contribution to journalArticlepeer-review


The recent detections of gravitational waves (GWs) reported by the LIGO and Virgo collaborations have made a significant impact on physics and astronomy. A global network of GW detectors will play a key role in uncovering the unknown nature of the sources in coordinated observations with astronomical telescopes and detectors. Here we introduce KAGRA, a new GW detector with two 3 km baseline arms arranged in an ‘L’ shape. KAGRA’s design is similar to the second generations of Advanced LIGO and Advanced Virgo, but it will be operating at cryogenic temperatures with sapphire mirrors. This low-temperature feature is advantageous for improving the sensitivity around 100 Hz and is considered to be an important feature for the third-generation GW detector concept (for example, the Einstein Telescope of Europe or the Cosmic Explorer of the United States). Hence, KAGRA is often called a 2.5-generation GW detector based on laser interferometry. KAGRA’s first observation run is scheduled in late 2019, aiming to join the third observation run of the advanced LIGO–Virgo network. When operating along with the existing GW detectors, KAGRA will be helpful in locating GW sources more accurately and determining the source parameters with higher precision, providing information for follow-up observations of GW trigger candidates.

Original languageEnglish
Pages (from-to)35-40
Number of pages6
JournalNature Astronomy
Issue number1
Publication statusPublished - 2019 Jan 1

Bibliographical note

Funding Information:
Cryogenic operation and underground construction are expected to be key technologies of the third-generation large-scale GW detectors28,29. For example, collaborative research and development activities between KAGRA and the next-generation projects, as represented by the ELiTES project, have been supported by the Japanese government and the European Commission in 2012–2017.

Funding Information:
The realization of the KAGRA project is made possible by enormous support from the scientific community as well as by great effort from researchers around the world. The upgraded bKAGRA is about to see the ‘first light’ in 2019. Nobody doubts the importance of GW research in astronomy, physics and also in engineering. We believe KAGRA will definitely contribute to these fields, especially to GW science, and help to broaden our understanding of gravity and of the Universe.

Publisher Copyright:
© 2019, Springer Nature Limited.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


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