银河系和高红移星系2175埃吸收特征研究

本项目将系统研究银河系和高红移星系的2175埃吸收特征。在银河系内，我们将利用最新释放的Galex紫外光谱（GR6）来测量约1500条视线方向上的2175埃吸收轮廓。利用这个大样本统计研究2175埃吸收载体在银河系内的大致分布和所处的天体物理环境。对于高红移星系，我们的研究对象是2175埃类星体吸收系统。我们将改进现有的探测方法并将其应用到SDSS DR8和SDSS-III BOSS的类星体光谱数据上，预计得到一个容量约200的2175埃类星体吸收系统样本。将对其做统计分析并探讨2175埃吸收物质随红移的演化。我们也将利用地面的光学和近红外设备进行后续光谱观测，准确测量吸收系统的窄吸收线，并确定其天体物理环境,如金属丰度，尘埃凝聚，电离状态等参数。

We propose to study the 2175-Armstrong absorption feature in the Milky Way (MW) and high-redshift galaxies. For the MW case, we will measure the 2175-Armstrong absorption profiles in about 1,500 lines of sight using the newly released Galex UV spectra (GR6). With this large sample, we can study the spatial distribution of the 2175-Armstrong absorption carrier in MW and the astrophysical conditions giving rise to the absorption feature. For the high-redshift case, we will focus on studing the 2175-Armstrong QSO absorption line system (2175 QAL). We are going to update our current detection technique and apply the updated version to SDSS DR8 and SDSS-III BOSS QSO spectra. We expect to build a much larger 2175 QAL sample with a size of about 200. Then we will study the sample statistically and explore the evolution of 2175-Armstrong feature with cosmic redshift. We also will follow up the selected 2175 QALs with ground-based Optical and NIR spectroscopy facilities. By measuring the responsing narrow metal absorption lines, we can estimate the astrophysical conditions of 2175-Armstrong absorbers, such as the metallicity, dust depletion, ionization state.