Astronomers Use Gravitational Lensing To Weigh Most Distant Galaxy
October 17, 2013

Astronomers Use Gravitational Lensing To Weigh Most Distant Galaxy

Lee Rannals for - Your Universe Online

Using a gravitational lensing technique, astronomers were able to weigh one of the most distant galaxies in the universe.

Gravitational lensing is a technique used by astronomers that was first predicted by Albert Einstein's theory of relativity. As light from a very distant object moves through the universe, it can essentially be intensified by another object that is closer to Earth, reviving the light and making it possible for scientists to observe the far-away object.

Scientists can determine the mass of the matter that is bending the light, including the mass of the still-enigmatic dark matter. The lens helps to magnify the background light source, acting as a "natural telescope" that allows astronomers to take a detailed look at these distant galaxies.

Astronomers have discovered the most distant gravitational lens yet, and it was found completely by chance, according to Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany.

"I had been reviewing observations from an earlier project when I noticed a galaxy that was decidedly odd. It looked like an extremely young galaxy, but it seemed to be at a much larger distance than expected. It shouldn't even have been part of our observing programme," van der Wel, lead author of the paper published in Astrophysical Journal Letters, said in a statement.

Van der Wel was on a mission to find out more, so he began studying images taken with the Hubble Space Telescope as part of the CANDELS and COSMOS surveys. These pictures showed a mysterious object that looked like an old galaxy, but with some irregular features that showed he was looking at a gravitational lens.

The lensing mass observed by the astronomers is very distant, with the team predicting that the light traveled about 9.4 billion years to reach Earth. The amount of distortion caused by the lensing galaxy allows scientists to take a direct measurement of its mass. This provided an independent test for astronomers' usual methods of estimating distant galaxy masses.

"This has been a weird and interesting discovery. It was a completely serendipitous find, but it has the potential to start a new chapter in our description of galaxy evolution in the early Universe," Van der Wel concluded.