银河系电离氢区多频段射电复合线观测研究

星际介质的演化在恒星形成和星系演化中起关键作用。电离气体是星际介质的主要形态之一。它既是大质量恒星形成区的主要成分，又是广泛分布于银道面弥散介质的重要组分。射电复合线(RRL)是直接观测星际电离气体，探索其物理属性的最有效的方法之一。本项目基于Arecibo银道面电离气体巡天(SIGGMA)研究。它是迄今灵敏度最高的大天区连续采样RRL巡天。将其结果与国内上海65米，青海德令哈13.7米在不同波段开展多波段联合研究，进行HII区、光致离解区(PDR)、以及行星状星云的搜寻和认证，验证分析RRL压力展宽机制获得HII区电子密度的方法，并将此方法应用于巡天HII样本。计划将SIGGMA观测技术及研究方法应用于FAST相关巡天，为联合FAST与上海65米进行银道面电离气体的多频段RRL研究做好充分准备。

Interstellar medium (ISM) plays a crucial role in the star-forming process and galaxy evolution. Ionized gas is one of the main components of ISM, which is also the major part of massive star-forming regions and the diffuse ISM along the Galactic Plane. Radio recombination line (RRL) is an ideal tool to probe the ionized ISM. This study is based on the Survey of Ionized Gas in the Galaxy, made with Arecibo (SIGGMA). This RRL survey is fully sampling the entire Galactic Plane observable with the Arecibo telescope at 1.4 GHz. The data of this survey will permit a wide range of science, including studies of HII regions, planetary nebulae, the photo-dissociation regions (PDRs), and the extended low density medium (ELDM) etc. Combining with SIGGMA, this project is focused on a multi-band RRL study using the Shanghai 65 m and Delingha 13.7 m telescopes. As one of the crucial physical properties of HII regions, the electron density is derived though RRLs pressure broadening analysis. In the near future, the RRL survey with the multi-beam L-band of FAST will considerably enlarge the sample of known HII regions. This work will verify an ideal method to detect the Ne for a large sample of HII regions by using FAST and Shanghai 65m together.