利用引力透镜研究高红移星系

High redshift objects are one of the most interesting topics in modern cosmology. They provide important information in the early stage of galaxy evolution as well as cosmic reionization. Due to the large distance, they are extreamely difficult to observe. Gravitational lensing acts as cosmic telescopes, enable the study of faint, distance galaxies, which otherwise impossible. However, in order to use these telescopes, we need an accurate magnification map and error analysis. In reality, most of the distance objects are found so far are magnified by foreground lens. Some of them have been studied from morphology and spectrum. However,there are two difficulties: the sample of high redshift objects is very small, the estimated parameters of lensed galaxies are biased due to differential magnification. In order to obtain large sample and intrinsic properties. We plan to find optimal method of searching lensed high redshift galaxies, and correct the bias in estimation of the lensed galaxies. Therefore, we have three stages in this project: 1.we will adapt numerical simulations to find out the high efficient way of searching lensed high redshift galaxies. 2.we will reconstruct the mass distribution of galaxy cluster, detail structure and errors will be studied. 3. with the mass distribution we can build the magnification map for given background sources. In particular we will calculate the magnification map for different given redshift,and optimal region for searching lensed galaxies.We will calculate the magnification map across the source. With the help of multi-spectra, such as IFU, the intrinsic properties of the high redshift galaxy can be reconstructed.

暗能量冷暗物质模型（LCDM）作为最成功的宇宙学模型，已经能够解释大多数宇宙学观测，但这个模型本身还存在着一些问题亟需解决。 比如，暗物质的性质和星系的形成和演化。暗物质不能被直接观测，而高红移星系由于其遥远的距离而不容易被观测到。引力透镜是一种强大的工具来帮助我们研究这些问题：一是它可以使我们测量暗物质的分布，其次它还可以放大背景源的亮度和空间分辨率。引力透镜作为一种天然的宇宙学望远镜，可以用来研究高红移极早期的天体。然而我们需要详细的透镜模型，来计算它对背景源的放大率，才能得到真实的背景源信息。本项目分为几个步骤：1利用数值模拟寻找最佳的搜索被透镜放大星系方法。2结合强弱透镜，动力学等方法得到星系团的质量分布。3计算其对背景源的放大率，可以估计寻找高红移背景源的最佳区域，得到极早期背景天体的性质，由此来研究星系早期的形成。

本项目主要期望利用引力透镜来研究高红移星系性质。当前天体物理学中对星系的形成与演化还存在很多未知因素。而高红移星系提供了非常好的研究星系早期形成演化的样本。但是由于其非常远的距离而无法直接观测，引力透镜的放大效应使得我们有机会观测超高红移的天体。然而为了得到精确的引力透镜的放大率，我们需要得到精确的引力透镜模型，所以引力透镜测量中的各种系统误差需要仔细的修正。我们在本项目中对未来观测的一种系统误差做出高精度的分析并给出修正方法。我们还给出了用透镜限制前景星系团和大尺度结构的两种分析。此外我们还利用积分场光谱给出了临近星系物理性质的详细分析。我们在研究射电源时，发现星际介质对射电源也产生折射，产生一种等离子体透镜现象。我们对此种现象给出初步分析。