Gravitational lensing

TL;DR

This paper provides a concise overview of gravitational lensing with a focus on radio and VLBI techniques, highlighting its basic principles, historical discovery, and potential for future research, aimed at radio astronomers in other fields.

Contribution

It offers a general overview of gravitational lensing tailored for radio astronomers, emphasizing VLBI aspects and illustrating with the lens B0218+357 case.

Findings

Discussion of the discovery of the first gravitational lens

Overview of lensing applications in radio astronomy

Potential for future research with lens B0218+357

Abstract

This is a short and biased review of gravitational lensing with emphasis on the radio and especially VLBI aspects. We briefly explain the basic idea and give a short sketch of the discovery of the first lens, before we more systematically discuss the general fields that can be studied with lensing. We intentionally omit the details the average lensing expert would like to see and instead try to give a very general overview addressed to the radio astronomer working in some other field. The lens B0218+357 is presented as an example to show many aspects of lensing in a case that already has led to interesting results but still has additional potential for the future.