BellaOnline Forums Education Astronomy G is for Gravitational Lens *new*

We have optical lenses in telescopes, cameras and eyes. They're made of transparent material, and they focus light. However astronomers now make use of gravitational lenses to detect distant galaxies, dark matter and extrasolar planets. What's a gravitational lens made of, and how does it work?

ABC of Astronomy – G is for Gravitational Lens

Who could resist a cosmic smiley? Here is the cluster of galaxies called SDSS J1038+4849.

There are trillions of stars in the cluster, which is about 4.5 billion light years away. Even farther away are more galaxies - they're about 7.5 billion light years away. J1038 is acting like a lens.

Two elliptical galaxies in this lensing cluster form the "eyes" and there's a smaller galaxy that gives us the "nose". The sides of the "head" and the "smile" are the more distant galaxies. Their light shows up as arcs in the distorted space. There's another example of this in my article.

The inset in this picture is an image of a galaxy that existed 400 million years after the Big Bang. We exist 13.8 billion years after the Big Bang, so the galaxy was around when the Universe was only 3% of its present age. It was a small galaxy – at least at the time – around the size of a Milky Way satellite galaxy called the Large Magellanic Cloud. It was forming stars at a rapid rate, so it may have grown into a large galaxy. It doesn't have a catalog number, but has been nicknamed Tayna “which means 'first-born' in Aymara, a language spoken in the Andes and Altiplano regions of South America.”

Tayna is distant and very faint. However the enormous gravity of massive galaxy cluster MACS J0416.1-2403 (about 4 billion light years away) has made it visible via gravitational lensing. The image is from the Hubble Space Telescope.

Credit: NASA, ESA, and L. Infante (Pontificia Universidad Católica de Chile)

Here is a picture of the Smithsonian.

If it were imaged with a gravitational lens about the mass of Saturn, viewed from the Natural History Museum, the Smithsonian might look like this!

(from B. McLeod, CASTLES project -- and extra thanks to Brian for the details on the mass assumed).

The Hubble Space Telescope has captured the image of the first-ever predicted supernova explosion. The reappearance of the Refsdal supernova was calculated from different models of the galaxy cluster whose immense gravity is warping the supernova’s light. (The supernova was named for Norwegian astronomer Sjur Refsdal was the first to propose using time-delayed images from a lensed supernova to study the expansion of the Universe.)

On 11 December 2015 astronomers not only imaged a supernova in action, but saw it when and where they had predicted it would be. In November 2014 scientists spotted four separate images of the supernova in a rare arrangement known as an Einstein Cross around a galaxy within MACS J1149.5+2223. The cosmic optical illusion was due a galaxy within the cluster warping and magnifying the light from the distant stellar explosion by gravitational lensing.