Large-Scale Far-Infrared Spectroscopic Study of the Galactic Center Region with High Spatial Resolution

我们之前的气球观测显示，远红外线[CII]线在朝向银河系中心的方向上是系统性的弱。我们提出了一个假设，即[CII]线的这种弱点可以归因于银河系中心的软星际辐射场。这一假说也可以解释该地区温暖分子云的普遍存在。此外，这一假说还导致了一个有趣的预测，即银河系中心区域的恒星形成率很低。然而，上述讨论大多依赖于空间分辨率很低的观测，而高空间分辨率观测一直是人们期待已久的。为了验证上述假说，我们使用球载望远镜对远红外线（CII）进行了高空间分辨率观测。这是一个与印度塔塔基础研究所（TIFR）的联合项目。TIFR负责1米球载望远镜，日本研究小组负责远红外法布里-珀罗光谱仪，我们在2000 - 2002财政年度期间进行了两次气球飞行，对银河系恒星形成区进行了高空间光谱观测。此外，我们分析了我们以前的气球观测和以前的星载任务的观测结果。通过这些活动，我们详细研究了星际辐射场与星际物质的相互作用，为理解银河系中心的物理过程奠定了基础。

Our previous balloon-borne observations revealed that the far-infrared [CII] line is systematically weak toward the Galactic center. We proposed a hypothesis that this weakness of the [CII] line can be attributed to the soft interstellar radiation field in the Galactic center. This hypothesis can also explain the ubiquitousness of warm molecular clouds in the region. Moreover, this hypothesis leads to an interesting prediction that the star-formation rate in the Galactic center region is low.However, most of the above discussions relied on observation with very poor spatial resolution, and high-spatial observations had been long-awaited.In order to check the above hypothesis, we performed high-spatial resolution observations of the far-infrared [CII] line using a balloon-borne telescope. This is a joint project with the Tata Institute of Fundamental Research (TIFR) in India. TIFR is in charge of the 1m balloon-borne telescope, and the Japanese group is in charge of the far-infrared Fabry-Perot spectrometer.We performed two balloon flights in the period of the fiscal year from 2000 to 2002, and made high-spatial spectroscopic observations of Galactic star-forming regions. Furthermore, we analyzed observational results of our previous balloon observations and previous space-borne missions. We thereby obtained very important information to understand the effects of radiation field on interstellar clouds.Through these activities, we made detailed study of interaction between interstellar radiation field and interstellar matter as a basis of the understanding the physical processed in the Galactic center.