Extremely rare ‘ring of fire’ galaxy discovered in the early universe

A violent, catastrophic collision between two galaxies has resulted in an extremely rare ring galaxy that lurks about 11 billion light years from Earth. The monstrous, donut-shaped galaxy makes stars in its huge ring 50 times faster than our home galaxy, earning a menacing nickname that Johnny and June Cash would surely dig: the cosmic “ring of fire”.

In a paper published in the journal Nature Astronomy on Tuesday, an international team of scientists, describes the ring galaxy R5519, which after searching data from the Hubble Space Telescope and the W.M. Keck Observatory in Hawaii. Of nearly 4,000 galaxies discovered in the data sets, R5519 was one of the brightest and showed a clear ring structure. So the team continued to investigate – and quickly found that they had found something unusual.

“It is a very strange object that we have never seen before,” says Tiantian Yuan, astronomer at Swinburne University in Australia and first author of the study. “The giant hole in this galaxy was caused by a head-on collision with another galaxy.”

Yuan and her team examined the properties of R5519 and gathered clues as to how it had formed. They ruled out gravitational lenses or a galaxy fusion because of their unusual structure and discovered a companion galaxy nearby – G5593. They suspect that this cosmic neighbor is the “intruder” galaxy that could have collided with R5519 about 40 million years ago.

The two galaxies must have knocked into each other fairly frontally – a galactic porthole – and it is likely that a star disk was already present in R5519. When G5593 crashed through the galaxy, it split the disk through its guts and a wave of stars expanded from the center, as seen in the GIF above.

“Collision formation from ring galaxies requires that a thin disk be present in the ‘victim’ galaxy before the collision occurs,” said Kenneth Freeman, astronomer at the Australian National University and co-author of the paper, in a statement.

If R5519 is caused by a major collision that would make it an extremely rare cosmic phenomenon. Only one out of 1,000 galaxies in the local universe is formed in this way. Remarkably, the early universe was much crowded, so the belief was that this type of collision could have been more common. Yuan suggests the dates tell a different story.

“People used to think we would find more of these collision ring galaxies in the young universe simply because there were more collisions back then,” she says. “We think that’s not the case.”

There are still some “unsolved puzzles” around the ring of fire, says Yuan. “We don’t know whether this ring was a first ring after the collision or the second ring.” She has more data from W.M. Try to fix this problem.

Astronomers need to collect more data to ensure that the ring is caused by a collision rather than natural evolution. The authors of the paper write the imaging of NASA’s James Webb Space Telescope, to be launched soon (and recently assembled) will be able to solve any remaining questions. Yuan says she has already discovered another ring galaxy that was probably caused by a head-on collision – and is a billion years older than the “ring of fire”.