Derivation of the lens equation
As discussed in Chap. 2, the gravitational lens phenomenon is important mainly for distant, extragalactic sources (z ≳ 1) and deflectors (z ≳ 0.05). The corresponding theory must, therefore, account for (i) the bending and distortion of light bundles by nearly isolated, bound masses, and (ii) the imbedding of sources, deflectors, and observers into their cosmological environment, how this affects the propagation of light, and, in particular, the relations between observables of sources and lenses. The first three sections of this chapter are devoted to the first topic. The fourth section contains a summary of those aspects of cosmology which are relevant for lens theory, together with some background material. On this basis, the second topic is treated in Sects. 4.5 and 4.6. Finally, in Sect. 4.7 we consider some aspects of wave optics, in preparation for chap. 7.
KeywordsDust Microwave Coherence Refraction Fermat
Unable to display preview. Download preview PDF.