The Sciences

The Large Cryogenic Gravitational-wave Telescope

Cosmic VarianceBy Daniel HolzJun 25, 2010 12:25 PM


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I am presently in Japan, participating in the Gravity and Cosmology workshop at the Yukawa Institute for Theoretical Physics on the Kyoto University campus. The big news here is that the Large Cryogenic Gravitational-wave Telescope (LCGT) was just approved for funding! I believe that this is the press release, as witnessed by the exclamation mark at the end of the title (a Japanese speaker will no doubt correct me if I'm wrong). Apparently they have been granted roughly half of their estimated price tag (of >$200 million). This is a critical step, and I am told that once the Japanese government commits funds, it is highly unlikely to change its mind down the road. So LCGT is a huge step closer to becoming a reality. We have waxed poetic about gravitational-wave detectors before (here, here, and here). These instruments are truly amazing feats of engineering, with the power to unlock a whole new window on our Universe. LCGT would be even more impressive than the current instruments (LIGO and Virgo): it takes its 3-kilometer long power-recycled Fabry–Perot–Michelson interferometer arms, and places them one kilometer underground (to reduce seismic noise, which sets the low-frequency [<10 Hz] noise floor). As if that's not enough, it also cools its mirrors to ~20 degrees above absolute zero (which reduces thermal noise, which sets the intermediate-frequency [10--100 Hz] noise floor). As it happens, I am in the midst of finishing a project with Samaya Nissanke (at JPL) and Scott Hughes (at MIT), trying to determine how well various gravitational-wave networks detect gravitational-wave standard sirens (stellar mass black hole and/or neutron star binary inspirals; more on why these are interesting in a future post). In particular, we are finding that adding LCGT to the expected Advanced LIGO-Virgo network increases the number of detected binaries by 50%, and generates more uniform sky coverage. LCGT will substantially enhance our view of the gravitational-wave sky, and will improve the science coming out of all the upcoming gravitational-wave detectors. Congratulations to the Japanese for pushing this observatory forward!

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