Gravitational Lensing
What is Gravitational Lensing?
Gravitational lensing is the bending of light by the gravitational field of a massive object. This phenomenon has a variety of astronomical applications: for example, it can be used as a natural telescope, magnifying distant sources into view; it can probe the density profile of galaxies and galaxy clusters, testing dark matter theories; and much more. The related field of microlensing has been used to search for low mass extrasolar planets, and to investigate the structure of quasars. Members of our group carry out computer simulations and observations of gravitational lensing.
Current research areas
Quasar Microlensing
Quasars, also known as quasi-stellar objects or QSOs, are luminous objects that are so distant that they appear pointlike in our images. When they are gravitationally lensed by an intervening galaxy, they can be multiply imaged. Often, assuming that the lens has a smooth mass distribution is adequate. However, in reality, galaxies are composed of stars and other compact objects, and are lumpy on small scales. Amazingly, this can actually change the brightnesses of the images, and these can vary with time in rather funky ways. We investigate these phenomena through the use of computational simulations.
Lensing by Galaxies
More Information
For more information contact Geraint Lewis or see the Gravitational Astrophysics Group website