File:Massive galaxy merger caught in the act (8787120628).jpg

Several telescopes have teamed up to discover a rare and massive merging of two galaxies that took place when the Universe was just 3 billion years old.

ESA’s Herschel space observatory first spotted the colliding duo, collectively called HXMM01, in images taken with longer-wavelength infrared light, as shown in the image at left. Follow-up observations from many telescopes helped determine the extreme degree of star-formation taking place in the merger, as well as its incredible mass – each galaxy boasts a stellar mass equal to about 100 billion Suns and an equivalent amount of gas.

The image at right shows a close-up view, with the merging galaxies circled. The red data are from the Smithsonian Astrophysical Observatory's Submillimeter Array (SMA) atop Mauna Kea, Hawaii, and show dust-enshrouded regions of star formation. The green data, taken by the National Radio Astronomy Observatory's Very Large Array (JVLA), near Socorro, New Mexico, show carbon monoxide gas in the galaxies. In addition, the blue shows starlight. A bridge of material connects the two galaxies, showing they are interacting.

The blue blobs outside of the circle are galaxies located much closer to us. These near-infrared light observations are from NASA's Hubble Space Telescope and the W.M. Keck Observatory atop Mauna Kea, Hawaii.