STUDY ON GRAVITATIONAL WAVES FROM COALESCING BLACK-HOLE MACHO BINARIES

将一台20m基线激光干涉仪引力波探测器从东京搬到神冈煤矿，那里的地震噪声比东京低两个数量级，其灵敏度和稳定性得到了显著提高。获得的位移灵敏度为1.2x10^-18；m/√&lt；Hz&gt；与TAMA300型引力波探测器获得的世界最高灵敏度相当。它的灵敏度也足以探测到距离地球1kpc、S/N为10的致密双星合并产生的引力波。稳定的运行不仅得益于较低的地震噪声环境，而且新安装的自启动系统，在2001年实现了超过2000小时的观测，在某些选定的11天内，最佳运行率达到99.8%。我们还在2001年夏天用TAMA300演示了我们银河系中第一次由致密恒星(如马赫黑洞)双星激发的符合引力波观测。巧合的是，采集的数据总计709个小时。在用一步搜索法选择引力波候选者后，重合分析检查了到达时间、质量参数和S/N比的一致性。初步结果是，没有发现引力波信号。这一结果有望给引力波搜索带来一个新的上限。

A 20-m baseline laser interferometer gravitational wave detector was moved from Tokyo into the Kamioka mine, where the seismic noise was lower by two orders of magnitude than in Tokyo, and its sensitivity and stability were drastically improved. The obtained displacement sensitivity of 1.2 x 10^<-18> m/√<Hz> was comparable with the world best sensitivity obtained by TAMA300 gravitational wave detector. Its sensitivity was also enough to detect gravitational waves from compact binary star coalescences within 1 kpc from the Earth with S/N of 10. The stable operation, which was enabled by not only the lower seismic noise environment but also a newly installed self restart system, realized over 2000 hours observation in 2001 and the best operation rate of 99.8% in some selected 11 days. We also demonstrated the first coincidence gravitational wave observation from compact star (such as a MACHO black hole) binary inspiraling in our galaxy with TAMA300 in the summer of 2001. The data taken coincidentally totaled up to 709 hours. After selecting the gravitational waves candidates by using one step search, the coincident analysis checked arrival time, mass parameters and S/N ratio consistency. As a preliminary result, no gravitational wave signal was found. This result is expected to put a new upper limitation on gravitational wave search.