Radio Microlensing: Past, Present & Near Future

Abstract

Strongly correlated non-intrinsic variability between 5 and 8.5 GHz has been observed in one of the lensed images of the gravitational lens B1600+434. These non-intrinsic (i.e. ‘external’) variations are interpreted as radio-micro-lensing of relativistic μas-scale jet components in the source at a redshift of z =1.59 by massive compact objects in the halo of the edge-on disk lens galaxy at z =0.41. We shortly summarize these observations and discuss several new observational and theoretical programs to investigate this new phenomenon in more detail.