장-레프스달 렌즈의 특성과 응용 = Optical Properties of Chang-Refsdal Lens and its Applications

다국어 초록 (Multilingual Abstract)

The gravitational lens system consisting of two mass points with very large mass ratio is basic concept for the Chang-Refsdal lens system, which in fact is known to be a two-body gravitational lens model. Light source of the lens system is taken to be QSO(Quasar Stellar Object). We reexamine optical properties of the system in context with optical shear. The caustic structures of different gravitational lens models are also discussed. It is also investigated how accurately the Chang-Refsdal lens approximation would be applied to n-body problem. It is shown that the Chang-Refsdal lens is accurate enough for the lensing system with the parent shear equal to that of the perturbing mass. One could thus apply the Chang-Refsdal lens model into n-body lensing system.