We have set a new upper limit on the stochastic gravitational-wave background using two prototype torsion-bar antennas (TOBAs). A TOBA is a low-frequency gravitational-wave detector with bar-shaped test masses rotated by the tidal force of gravitational waves. As a result of simultaneous 7-hour observations with TOBAs in Tokyo and Kyoto in Japan, our upper limit with a confidence level of 95% is Ωgwh02<1.9×1017 at 0.035-0.830 Hz, where h0 is the Hubble constant in units of 100 km/s/Mpc and Ωgw is the gravitational-wave energy density per logarithmic frequency interval in units of the closure density. We successfully updated the upper limit and extended the explored frequency band.
|ジャーナル||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|出版ステータス||Published - 2014 1 22|
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