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Cosmic tsunamis can wake up comatose galaxies

Unfortunately the new lease on life is too much for these aging galaxies to handle. Their newfound star-forming abilities quickly dissipate, researchers say.

By Brooks Hays
Cosmic tsunamis can wake up comatose galaxies
A composite image details the regions of new star formation in the previously lifeless Sausage galaxy. Photo by Lieden Observatory/Royal Astronomical Society

LEIDEN, Netherlands, April 24 (UPI) -- Just as seemingly lifeless coma patients can wake up after years of deep sleep, all-but-dead galaxies can also be shocked back to life.

New research suggests cosmic tsunamis created by colliding galaxies can act as a sort of defibrillator for lifeless galaxies. Until now, researchers didn't think galaxies were affected by these shockwaves.

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The so-called tsunamis are a product of galaxies congregating and colliding -- the result of big galaxies absorbing smaller galaxies, just as growing cities swallow up nearby towns and suburbs. When clusters bump and grind, and galaxies merge, large amounts of energy are released.

Recently, researchers were able to watch as a shockwave created by a galactic merger rippled through one of the two galaxies -- a cluster with the official name CIZA J2242.8+5301, but nicknamed "Sausage." The galaxy is located 2.3 billion light-years away near the constellation of Lacerta.

Using the Isaac Newton and William Herschel Telescopes on the Canary Islands' La Palma, as well as the Subaru, CFHT and Keck Telescopes on Hawaii, researchers were able to observe the shockwave as it jumpstarted a spate of star formation in previously dead and decaying galaxies.

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"Much like a teaspoon stirring a mug of coffee, the shocks lead to turbulence in the galactic gas," Andra Stroe, an astronomer at the Leiden Observatory in the Netherlands, explained in a recent press release. "These then trigger an avalanche-like collapse, which eventually leads to the formation of very dense, cold gas clouds, which are vital for the formation of new stars."

Unfortunately the new lease on life is too much for these aging galaxies to handle. The spurt of rapid star formation results in a litany of bright stars that burn fast and die young, resulting in supernovas that expel what little star-forming materials the galaxies have left.

The new work -- conducted by Stroe and his research partner David Sobral, an astronomer at Leiden and the University of Lisbon -- is detailed in two papers, both published this week in the Monthly Notices of the Royal Astronomical Society.

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