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Newswise An international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA) -- among other telescopes -- has obtained the best view yet of a collision between two galaxies when the Universe was only half its current age.

To make this observation, the team also enlisted the help of a gravitational lens, a galaxy-size magnifying glass, to reveal otherwise invisible detail. These new studies of galaxy HATLAS J142935.3-002836 have shown that this complex and distant object looks surprisingly like the comparatively nearby pair of colliding galaxies collectively known as the Antennae.

"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," explains lead author Hugo Messias of the Universidad de Concepcin in Chile and the Centro de Astronomia e Astrofsica da Universidade de Lisboa in Portugal. "Einstein predicted in his theory of General Relativity that, given enough mass, light does not travel in a straight line but will be bent in a similar way to a normal lens."

Cosmic lenses are created by massive structures like galaxies and galaxy clusters, which bend light from objects behind them due to their strong gravity -- an effect called gravitational lensing. The magnifying properties of this effect allow astronomers to study objects that would otherwise be invisible and to directly compare local galaxies with much more remote ones, when the Universe was significantly younger.

For these gravitational lenses to work, however, the foreground lensing galaxy and the one beyond need to be precisely aligned.

"These chance alignments are quite rare and tend to be hard to identify," adds Messias, "but, recent studies have shown that by observing at far-infrared and millimeter wavelengths we can find these cases much more efficiently."

HATLAS J142935.3-002836 (or H1429-0028 for short) is one of these sources and was found in the Herschel Astrophysical Terahertz Large Area Survey (HATLAS). It is among the brightest gravitationally lensed objects in the far-infrared regime found so far, even though we are seeing it at a time when the Universe was just half its current age.

To study this object in further detail, the astronomers started an extensive follow-up campaign using an impressive collection of incredibly powerful telescopes, including the Hubble Space Telescope, ALMA, the Keck Observatory, and the VLA, among others.

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Best View Yet of Merging Galaxies in Distant Universe