From the remote Atacama desert, an array of telescopes has captured a spectacular image of a celestial wave crashing in the night sky. The spiraling structure created from passing galaxies has helped confirm theories about galaxy collisions. And it was seen at just the right time.
Galaxies like IC 2163 (left) rotate once every 100 million years, so the eyelid-like structure depicted in the image above is only intact for a few tens of millions of years. That timescale might seem huge to human standards but it’s a narrow window in cosmic terms. Once the galaxy makes a complete rotation, the eyelid gets swallowed up like a surfer in a crashing wave. The structure itself is also rather rare.
“It takes a special orientation of the galaxies for one of them to become ocular during an interaction,” co-author Bruce Elmegreen told Digital Trends.
Using data captured by the Atacama Large Millimeter/submillimeter Array (ALMA), Elmegreen, lead author Michele Kaufman, and their team were able to measure the movement of carbon dioxide gas in the galaxy’s unique ocular feature with better detail than ever before. These measurements showed a strong central shock, which confirmed computer models.
“As soon as I saw in the nearly raw data that there was a velocity difference in excess of 100 kilometers per second across the narrow width of the eyelids, I knew that these high resolution observations of the gas motions revealed how eyelid structure develops and thus confirmed predictions of numerical models,” Kaufman said.
“We [caught] it during the relatively brief time … when one of the galaxies exhibits an eyelid structure and this allows the specific test.” she said.
Kaufman and Elmegreen compare the galaxy’s mechanics to that of a tsunami. “Both are traveling at high speeds relative to their surroundings,” Kaufman explained, “until they reach something that causes them to abruptly slow down.”
A paper detailing the findings was presented in Astrophysical Journal.