A great view of colliding galaxies, thanks to magnifying glasses in the sky


This diagram shows how the effect of gravitational lensing around a normal galaxy focuses the light coming from a very distant star-forming galaxy merger to created a distorted, but brighter view. (ESA/ESO/M. Kornmesser)

Remember "lensing galaxies"?  They're so big that they bend the light around them, serving as a natural magnifier of smaller galaxies lurking behind.

With the help of several telescopes (including the Hubble) and an international team of astronomers, one of these gravitational lenses has revealed our best ever view of an ancient galactic collision. The two galaxies are pictured as they were when the universe was just half its current age, the astronomers report.

The collision, using combined images from Hubble and Keck-II (NASA/ESA/ESO/W. M. Keck Observatory) The collision, using combined images from Hubble and Keck-II (NASA/ESA/ESO/W. M. Keck Observatory)

Interacting galaxies don't crash into each other like speeding cars. When multiple galaxies meet (a fairly common occurrence), they can merge into one or change each other's morphology a bit before moving on.

The galaxies (known together as H-ATLAS J142935.3-002836) resemble a collision called the Antennae Galaxies. The latter collision is much closer to our planet, and has been imaged quite clearly using the Hubble before. But H-ATLAS J142935.3-002836 turns more than 400 times the mass of the Sun in gas into new stars each year, which is around ten times the rate of the Antennae system.

It was a multi-telescoping effort that revealed clear images of the combined system. But the Hubble can track down the traces of these perfectly aligned cosmic lenses, allowing astronomers to devote their efforts to the right nooks and crannies of the universe.

 

Rachel Feltman runs The Post's Speaking of Science blog.

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Rachel Feltman · August 25, 2014