|
We propose an EVN 5 GHz and 23.1 GHz study of a carefully-selected sample of 43 bright compact radio sources selected from the Astrogeo X-band archives. They are lens candidates having multiple compact components and the aim is to search for mass condensates on mass scales of 10^6 to 10^10 solar masses -- a parameter space almost entirely unconstrained by optical strong/weak lensing surveys or micro-lensing surveys. The parent sample consists of 12,868 objects previously detected with the VLBA at X-band. Higher resolution at 23.1 GHz and higher sensitivity at 5 GHz will enable us to confirm or reject these lens candidates. We wish to search for lensing which might be caused both by halos composed of exotic forms of dark matter or primordial black holes. The same observations could reveal binary AGN. |