A massive collision of galaxy clusters sent a shockwave 1 million light-years into space

Two clusters of galaxies collided, creating a massive shock wave spanning over 1.6 million light-years in length. NASA’s Chandra X-ray Observatory spotted the shock wave earlier this month. NASA says that these galactic collisions release large amounts of energy. Plus, it could help us better understand some of the physics that make up our solar system.

Galactic collisions lead to intriguing research

Researchers publish a new study on these colossal galactic collisions in The Monthly Notices of the Royal Astronomical Society. The document is currently visible on the arXiv preprint server. In it, the researchers detail how these collisions release their energy and create “collisionless shockwaves” that can travel millions of light-years.

Although the idea of ​​a collisionless shock wave may seem impossible, especially when we’re talking about colliding clusters of galaxies, it’s important to note that just because two clusters collide doesn’t to the other that a physical collision occurs. Galaxy clusters are made up of more than the galaxies they contain.

In fact, the majority of a galactic cluster is a huge halo of dark matter and a cloud of gas known as the intra-cluster medium. It is these two components that often cause the collisionless shock waves that scientists have studied. It is also these components that often crash together in galactic collisions like that of Abel 2146.

Crash together

Image source: X-ray: NASA/CXC/Univ. of Nottingham/H. Russell et al. ; Optics: NAOJ/Subaru

It’s how these two components collide that intrigue scientists. And, some say, it could help us better understand the physics that drives our universe. For starters, in the galactic collision of Abel 2146, one cluster falls through the other. In doing so, it creates two shock waves, an arc shock and an upstream shock.

The arc shock from the galactic collision is compressed gas in front of the falling cluster, researchers say. However, the upstream shock is much more complex. Instead, it forms when gas that is removed from the incoming cluster is left behind and interacts directly with in situ gas in the cluster it passes through.

It was these reactions that created the collisionless shock waves that Chandra observed. Moreover, it is the arc shock wave that is 1.6 million light-years long. The researchers also measured the width of the shock wave for the first time. They confirmed the theories that the upstream shock is narrower than the front shock because it is younger.

What’s more, NASA says understanding these shock waves could also help us better understand the explosions our Sun releases.