The Half-Astrophysicist Blog

The Chesire Cat Gravitational Lens

I just found this gravitational lens from the Sloan Digital Sky Survey which has been dubbed the Chesire Cat.

Hopefully you can see the eyes and the smile near the center of the image.

The two eyes of the cat are two massive elliptical galaxies about 4.5 billion light years away.  These galaxies are bending and distorting the light of more distant galaxies (at least two different galaxies have been identified) to form the smile.  These more distant galaxies are about 8 billion light years away.

Gravitational lensing is one of those weird things predicted by Einstein.  He said that a massive object (say a galaxy) could warp space.  Light from a more distant object would follow this strangely curved space time and creates all kinds of interesting patterns such as arcs, crosses and circles.

Gravitational lenses are useful for mapping dark matter.  By looking at the pattern we see, we can calculate how much matter is present and how it is distributed.  We can also look at the matter we see and conclude that what we don’t see is, well, dark matter!

You can see the Chesire Cat and a bunch of other gravitaitonal lenses from the SDSS at at the CASSOWARY Graviational Lenss page.


October 30, 2008 - Posted by | Uncategorized

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