Gravitational Lensing as a Probe of Cold Dark Matter Subhalos
Figure 3
Small and large sources. (a) A galaxy surrounded by a dark matter halo produces multiple images of a small background light source (e.g., an optical quasar). (b) For a larger background source (e.g., a galaxy or a radio-loud quasar), the macroimages may be stretched into arcs or even a complete Einstein ring.
