Gravitational lensing from the faraway galaxy has never been observed behind a cluster at such an enormous distance, the researchers said.
Since this galaxy cluster is so distant — 10 billion light-years away — it existed when the universe was only one-quarter of its present age. The universe is estimated to be roughly 13.7 billion years old. Current theories for how the universe evolved suggest that relatively few of these galaxy clusters were present when the universe was in its infancy, the researchers said. [The Universe: Big Bang to Now in 10 Easy Steps]
Still, finding this galaxy cluster represents a serendipitous astrophysical discovery in itself, since the astronomers were scanning only a small 9-square degree section of the sky. For comparison, if you extend your arm in front of you and hold up your index finger, you will be covering approximately 1 square degree of the sky with your finger, Gonzalez explained.
"So finding a massive cluster at that range that is also gravitationally lensing is a real long shot, even if you were looking at the whole sky," he said.
The astronomers originally found the galaxy cluster using NASA's infrared Spitzer Space Telescope, but evidence of the gravitational lensing was seen in images taken by the Hubble Space Telescope in 2010.
To follow up on this find, and to narrow down the cluster's mass and distance, the researchers used data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) radio telescope in the Inyo Mountains in California, and NASA's Chandra X-ray Observatory in space.