Gravitational Lensing

What is Gravitational Lensing?

Gravitational lensing, loosely speaking, refers to the fact that light rays from a distance source are deflected and distorted by intervening mass distributions. Gravitational lensing is commonly divided into three areas. All these have important implications for the dark matter problem, galaxy structures and cosmology.

The first is the so-called strong gravitational lensing, where a single background source is distorted into multiple images , spectacular giant arcs, as in CL2244 and A2218 (shown above), and, in some cases even complete rings .

The second area is gravitational microlensing, where we observe the time-changing magnification of a background source due to lensing, please refer to my brief introduction elsewhere.

The third lensing pheonomenon is the so-called weak lensing, where we see the weak distortions of many distant background galaxies by intervening matter. The effect is weak, but ubiquitous, and hence has very diverse applications in astrophysics.

Some Groups Working on Gravitational Lensing

For groups working on microlensing, see my introduction on microlensing

Literature on Gravitational Lensing

To learn more about lensing, I recommend the following reviews:

This page is under construction. Last updated on Nov. 17, 1999.