Gravitational Wave Astronomy using a Sensitive Laser Interferometer

引力波天文学有可能为我们带来关于超新星、双中子星或双星黑洞的合并或宇宙早期阶段的新信息，这些信息是通过电磁波、中微子等其他观测手段无法获得的。目前还没有人成功探测到引力波。然而，在不久的将来，通过开发灵敏和稳定的长臂激光干涉仪，似乎有可能探测到来自外星的真实引力波。在这项研究中，在国家天文台三中园区开发并建造了两个300米长臂的灵敏激光干涉仪TAMA300，目的是建立实现公里级激光干涉仪的技术，并作为望远镜来观察机会探测附近星系内产生的引力波。我们成功地研制出了高功率、超稳定的激光和非常高质量的反射镜等。1999年夏天，我们比世界上其他大型激光干涉仪、美国的LIGO(4公里)、法国和意大利的VERGO(3公里)和英国和德国的GEO(600米)合作成功地完成了第一次观测运行。在2000年夏天，TAMA300已经达到了最高级别的灵敏度，并展示了足够的能力来探测我们银河系内双星中子星合并产生的引力波。2001年夏天，我们进行了为期50天的长期科学运行，获得了1000多个小时的观测数据。运行后，我们在干涉仪上安装了一个能量回收镜，并在短时间内成功地运行了它。未来几年，计划将TAMA300与LIGO和GEO重合运行，形成一个引力波搜索的全球网络。

Gravitational wave astronomy has a potential to bring us new informations about supernovae, coalescence of binary neutron stars or binary black holes, or early stage of the Universe, which cannot be obtained by other means of observation such as electromagnetic waves, neutrino, and so on. Nobody has yet succeeded to detect gravitational waves. However, it seems possible in the near future to detect a realistic gravitational wave from an extraterrestrial origin, by developing sensitive and stable laser interferometers with very long arms.In this study, a sensitive laser interferometer with two 300m long arms, TAMA300, has been developed and constructed on Mitaka campus of the National Astronomical Observatory, for the purpose to establish technologies for realizing a km-scale laser interferometer, and has been operated as a telescope to watch for a chance to detect a gravitational wave generated within nearby galaxies.We have succeeded to develop a high-power and ultra-stable laser, very high quality mirrors and so on, which are all essential to the high sensitive interferometer. In the summer of 1999, we performed the first observational run successfully in advance of the other large-scale laser interferometers around the world, LIGO (4km) in USA, VIRGO(3km) collaboration between French and Italy, and GEO(600m) collaboration between England and Germany. In the summer of 2000, TAMA300 has reached a top-level sensitivity and has demonstrated a sufficient capability to detect a gravitational wave from a coalescence of binary neutron stars within our Galaxy. In the summer of 2001, we performed a long-term scientific run for 50 days and obtained the observational data for more than 1000 hours. After the run, we have installed a power-recycling mirror to the interferometer, and succeeded to operate it in a short time.In the coming years, coincident runs of TAMA300 with LIGO and GEO are planned to make a global network for the gravitational-wave search.