Weak Lensing with Radio Continuum Surveys

Weak gravitational lensing is a powerful probe of cosmology and has emerged as a key probe for the Dark Universe. Up till now this science has been conducted mainly at optical wavelengths. Current upgraded and future radio facilities will provide greatly improved data that will allow lensing measurements to be made at these longer wavelengths. In this proceedings I show how the larger facilities such as the SKA can produce game changing cosmological measurements even compared to future optical telescopes. I will also discuss how radio surveys can also provide unique ways in which some of the most problematic systematic errors can be mitigated through the extra information that can be provided in the form of polarisation and rotational velocity measurements. I will also demonstrate the advantages to having overlapping optical and radio weak lensing surveys and how their cross-correlation leads to a cleaner extraction of the cosmological information. Key to the realisation of the great promise of radio weak lensing is the suitable measurements of galaxy shapes in the radio data, either from images or from the visibility data. I shall end with a description of the key issues related to this matter and the radioGREAT challenge which has been proposed to address them.