A New Gravitational Lens Phenomena by Cluster of Galaxies and the Measurement of Cosmological Constant

本研究探讨了利用引力透镜来确定宇宙学参数，特别是宇宙学常数的方法。以下是研究结果。透镜类星体图像之间的角间隔分布可以用来确定宇宙常数的上限。我们检验了在这项研究中起重要作用的放大偏差，并对此进行了更准确的估计。我们的结果表明，宇宙常数的存在不能被现有的观测所否认。星系团中的巨型发光弧的数量出人意料地多。我们研究了这个问题，发现宇宙常数的存在增加了弧线的预期数量。我们发现，用像斯巴鲁这样的大望远镜观测爱因斯坦环可能会对宇宙常数造成严重的限制。我们研究了利用背景星系相干扭曲产生的弱剪切场估计星系团质量分布的方法，并将该方法应用于Q0957+561和PG1115+080，得到了对哈勃参数的约束。

This study investigates methods to determine the cosmological parameters, particularly cosmological constant using gravitational lensing. The following are results of the study.1. The distribution of angular separation between images of lensed quasar can be used to put the upper bound for the cosmological constant. We examined the magnification bias which plays an important role in this study and obtained more accurate estimation for this. Our result shows that the existence of the cosmological constant cannot be denied by the presently available observations.2. The number of giant luminous arcs in clusters of galaxies is unexpectedly large. We examined this problem and found that the presence of the cosmological constant increase the expected number of arcs.3. We showed that the observation of Einstein rings using large telescope such as SUBARU may impose a severe constraint on the cosmological constant.4. We studied the method to estimate the mass distribution of cluster of galaxies using weak shear field created by coherent distortion of background galaxies and applied the method to Q0957+561 and PG1115+080 to obtain the constraint on the Hubble parameter.