Universe just recorded its most powerful sonic booms in Stephan’s Quintet

A galaxy has been observed moving at an astonishing speed of 3.2 million km/h, which then slams into four other celestial bodies, creating the most powerful shockwaves ever. The cosmic bashing occurred in Stephan's Quintet which houses five galaxies. One of the system's five galaxies, called NGC 7318b, collided with the other four.

Researchers say that the smashing led to an immensely powerful shock front similar to a "sonic boom from a jet fighter". The discovery was published in the journal Monthly Notices of the Royal Astronomical Society on November 22. The stunning observation was made by the William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) in La Palma, Spain.

The five galaxies were discovered nearly 150 years ago. The Stephan’s Quintet is a huge intergalactic field of debris. As the NGC 7318b raced through it, the field, which contains remnants of previous galactic collisions, was reactivated.

“Since its discovery in 1877, Stephan’s Quintet has captivated astronomers because it represents a galactic crossroad where past collisions between galaxies have left behind a complex field of debris,” lead author Marina Arnaudova, an astronomer at the University of Hertfordshire, said.

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“Dynamical activity in this galaxy group has now been reawakened by a galaxy smashing through it at an incredible speed of over two million mph, leading to an immensely powerful shock, much like a sonic boom from a jet fighter.”

The researchers say that the shockwave created was of a dual nature. “As the shock moves through pockets of cold gas, it travels at hypersonic speeds – several times the speed of sound in the intergalactic medium of Stephan’s Quintet – powerful enough to rip apart electrons from atoms, leaving behind a glowing trail of charged gas, as seen with WEAVE,” Arnaudova said.

However, when interacting with the surrounding hot gas, the shock, instead of "causing significant disruption", "compresses the hot gas, resulting in radio waves that are picked up by radio telescopes like the Low-Frequency Array (LOFAR),” explained Soumyadeep Das, a PhD student at the University of Hertfordshire.

What is Stephan's Quintet?

Stephan's Quintet was discovered by French astronomer Édouard Stephan in the 19th century. It is around 290 million light-years from Earth and is a group of five galaxies that are "locked in a cosmic dance of repeated close encounters," according to NASA.