Tuesday, August 18, 2009

Stef's Research Explained: Gravitational Lenses

So I was supposed to do this in installments, but I'll just try and get it all out there now. Keep in mind this is her research that I'm explaining so I'll probably butcher it, but cut me some slack because I'm not an astronomer anymore. Anyways here goes nothing...

Gravitational lensing is a pretty sweet phenomena. Basically light that gets emitted from distant objects can be bent because of a large gravity source (like say a galaxy, black hole, quasar, etc). Sometimes, the light can be bent in our direction and it is this phenomenon that we can see some truly spectacular images.

In the picture above, I have carefully illustrated what happens. Normally light will propagate away from the source in straight lines, but if there is a large gravitational presence the light will bend. Depending on how many different directions the light will bend, we can see multiple images of the same source as demonstrated below.

If the source, lens (big gravity thing), and observer (us) are all aligned we can see something really awesome called an Einstein ring. Basically what happens is the light from the source gets warped into a ring shape around the lens. Here is the Wikipedia article about it if you care to learn more.

Stef's research this past summer involved determining characteristics of the lensing objects. The more massive the source, the more cool the lensing effect. She looked through a survey (basically a bunch of crappy images of large portions of the sky, which are only bad because it would take years to get it at a poor resolution) and figured out commonalities of these lenses. I include a presentation she made which has some sweet lens pictures and some of her data.

Speaking of surveys, I guess my next post should be about what I did in Puerto Rico... maybe.

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