Telescopes in space and on the Earth have collaborated to provide the clearest view yet obtained of a cosmic collision between two distant galaxies, astronomers say.
The light from the cosmic phenomenon reaching the Earth for us to gaze at has had to travel so far it is giving a view of the two galaxies from when the universe was just half as old as it is now, they say.
The unique view is made possible by a "lensing" galaxy, with gravity so strong it bends the light of the merging galaxies behind it.
When multiple galaxies sit in almost perfect alignment, as in this case, the galaxy closer to Earth can actually provide astronomers with a sharper view of galaxies or other cosmic objects behind it, due to the "lensing" and its magnifying effect.
"These chance alignments are quite rare and tend to be hard to identify," Hugo Messias, the lead author of a study on the colliding galaxies, said in a release.
"While astronomers are often limited by the power of their telescopes, in some cases our ability to see detail is hugely boosted by natural lenses created by the universe," he said.
The "collision" of the two galaxies, a fairly common occurrence, takes place almost in slow motion. Usually the two galaxies will either slowly merge with each other or cause changes in each other's shape before moving on into the vastness of space, astronomers say.
The galaxies, known together as H-ATLAS J142935.3-002836, are so distant it took a number of telescopes working together to gather the image. They included the Spitzer and Hubble space telescopes, plus instruments on Earth observatories including the Keck telescope in Hawaii, New Mexico's Very Large Array and the ALMA instrument in Chile.
The released image shows the two disc-shaped galaxies apparently colliding, a process that almost certainly is seeing new stars being created.
The image also shows a band of light passing across the two galaxies - this is the closer lensing galaxy doing its magnification trick to provide us with the vivid view of the cosmic smash-up going on in the distance behind it.
"The powerful synergy between the Herschel Space Observatory and our coordinated follow-up effort from ALMA, VLA, and other observatories around the world has dramatically improved our understanding of galaxy mergers when the universe was half its present age," says Shane Bussmann from Cornell University in New York.
