Development of Optical Fiber-based Multi-Object Spectrograph for Investigations of Galaxy Formation History

我们研制了一台新的近红外光谱仪，能够在多目标模式和/或二维模式下测量高红移星系的光谱，目的是通过对高红移星系和类星体的观测来研究系统的光谱研究。光谱仪的规格是，波长范围为0.8微米至1.8微米，多目标模式下的多重数为400，以及2-D模式(IFU模式)下的250。在2002-2004年的研制工作中，我们设计和制造了主聚焦机械/光学单元、采用新开发的光学元件的近红外光谱仪和大阵列探测器系统。截至2004年3月，我们一直在测试整个光谱仪的光纤狭缝图像，该系统将于2005财年第一季度在斯巴鲁望远镜上进行测试，然后将于2005年秋季进行光谱观测。在这些发展工作的同时，我们还研究了正常星系、射电星系和类星体等高红移天体，这些天体的数据是由斯巴鲁望远镜的独特的近红外光谱仪(OHS)和红外成像仪(Cisco)获取的。基于这些光谱和光度数据，我们通过测量铁、镁等金属元素的近红外发射线，发现了类星体环境的化学演化，并在高红移区发现了一两个大质量星系，具有明显的盘状特征。在上述发展和观测工作结果的基础上，我们计划利用我们的高多重数仪器的独特能力，继续对早期宇宙中的星系/类星体演化进行系统的研究。

We have developed a new near-infrared spectrograph capable of measuring spectra of high-redshift galaxies in the multi-object mode and/or in the 2-D mode, for the purpose of investigating systematic spectroscopic studies by survey observations of high-redshift galaxies and quasars. The specifications of the spectrograph are, the wavelength range of 0.8 to 1.8 microns, the multiplicity of 400 in the multi-object mode, and 250 in the 2-D mode (IFU mode). During the period of this developmental work from 2002 to 2004,we have designed and fabricated a prime-focus mechanical/optical unit, a near-infrared spectrograph with newly developed optical components, and a large array detector system. As of March 2004,we have been testing the fiber-slit images of the spectrograph as a whole, and the system will be tested on the Subaru Telescope in the first quarter of FY 2005,and then the spectroscopic observations will be made in the fall of 2005. Along with these developmental works, we have investigated high-redshift object such as normal galaxies, radio galaxies, and quasars, whose data were acquired by the unique near-infrared spectrograph (OHS) as well as the infrared imager (CISCO) at Subaru Telescope. Based on these spectroscopic and photometric data, we found chemical evolution of quasar environment by measuring near-infrared emission lines of metal elements such as Fe and Mg, and also found one or two massive galaxies at a high-redshift region with clear indication of disk feature. On the basis of the above results of developmental and observational works, we plan to continue systematic investigations of the galaxy/quasar evolution in the early universe by utilizing the unique capability of our high multiplicity instrument.