ALMA details merger of two massive, super bright galaxies

"Our current observations indicate that these two galaxies are indeed producing stars at a breakneck pace, about one thousand times faster than our home galaxy," researcher Dominik Riechers said.
By Brooks Hays  |  Nov. 13, 2017 at 4:55 PM
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Nov. 13 (UPI) -- ALMA has provided astronomers with new observations of the ongoing merger between two hyper-luminous starburst galaxies.

The galaxies, collectively known as ADFS-27, are extremely large and bright. Astronomers believe intense rates of star formation were triggered when the two galaxies first grazed each other as they began their prolonged merging process. This near-collision jump-started what some astronomers think is the best example of violent star formation yet observed.

"Finding just one hyper-luminous starburst galaxy is remarkable in itself. Finding two of these rare galaxies in such close proximity is truly astounding," Dominik Riechers, an astronomer at Cornell University, said in a news release. "Considering their extreme distance from Earth and the frenetic star-forming activity inside each, it's possible we may be witnessing the most intense galaxy merger known to date."

ADFS-27 is located 12.7 billion light-years from Earth, which means astronomers are viewing the dynamics of galactic evolution as they played out just a billion years after the Big Bang and the birth of the universe.

The cosmic object was first spotted by the European Space Agency's Herschel Space Observatory. Follow up observations were made using the Atacama Large Millimeter/submillimeter Array. The observations revealed remarkably intense regions of star formation. The intense stellar factories are fueled by the massive amounts of star-forming materials, gas and dust, surrounding the system -- 50 times more star-forming gas than is found in the Milky Way.

"Much of this gas will be converted into new stars very quickly," Riechers said. "Our current observations indicate that these two galaxies are indeed producing stars at a breakneck pace, about one thousand times faster than our home galaxy."

Unfortunately, the shell of dust and gas obscures much of the intense blue light emitted by young stars. Instead, the stellar light is absorbed by the gas and dust and reemitted in infrared form, which can be observed by ALMA.

"Due to their great distance and dustiness, these galaxies remain completely undetected at visible wavelengths," Riechers said. "Eventually, we hope to combine the exquisite ALMA data with future infrared observations with NASA's James Webb Space Telescope. These two telescopes will form an astronomer's 'dream team' to better understand the nature of this and other such exceptionally rare, extreme systems."

The latest ALMA observations show the duo remain 30,000 light-years apart. They will likely graze each other several more times before they collide head on and fuse into a single entity. The process will take several hundred million years.

Researchers described their observations of the unique galactic system in a new paper published this week in the Astrophysical Journal.

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