Colossal Shock Wave Rippling Across Space Is Bigger Than Our Entire Galaxy

 

A billion years ago, a massive collision between two galaxies produced two massive shock waves.

Today, the formations sparkle brightly in radio frequencies, so enormous they may easily cover the Milky Way galaxy's estimated 100,000 light-year diameter, spanning up to 6.5 million light-years through intergalactic space.

Now, using the MeerKAT radio telescope in South Africa, a team of astronomers has undertaken the most extensive analysis of these radio structures yet, yielding fresh insight into some of the most colossal events in the Universe.

"These structures are full of surprises and considerably more intricate than we first expected," says astronomer Francesco de Gasperin of the University of Hamburg and the Italian National Institute for Astrophysics.

"The shock waves function as enormous particle accelerators that accelerate electrons to speeds near to the speed of light. When these speeding electrons cross a magnetic field they emit the radio waves that humans see. \s" The shocks are interwoven by an elaborate pattern of light filaments that map the location of huge magnetic field lines and the places where electrons are accelerated."

Galaxy clusters are the largest gravitationally bound structures in the Universe. They can be absolutely gigantic, containing hundreds or thousands of individual galaxies. Galaxies and galaxy clusters travel along cosmic web filaments to cluster nodes, where they join to form larger clusters.

These massive events occur at high speeds, generating cluster-scale shock waves that travel through space at high speeds.

This particular cluster, called Abell 3667, is still coming together. At least 550 galaxies have been connected with it, and the shock waves are travelling through it at velocities about 1,500 kilometres per second (930 miles per second) (930 miles per second).

The shocks that are associated with cluster mergers are known as radio relics, and they can be used to explore the parameters of the intergalactic space within the cluster, known as the intracluster medium, and intracluster dynamics.

Abell 3667 is a good target for such probes because it is quite close to us and also rather big, at roughly 700 million light-years away.

Because the cluster sits in the southern sky, researchers were able to look at it with one of the most sensitive radio telescopes in the world. MeerKAT is a forerunner to and pathfinder for the Square Kilometre Array (SKA) that is now being created across Australia and South Africa to provide an unprecedented radio eye on the sky.

MeerKAT's observations, and those of the Australian Square Kilometer Array Pathfinder, are giving us a taste of the future; not just for the SKA, projected to see first light in 2027, but what we can find now.

The researchers write in their paper, "Our observations have revealed the complexity of the interplay between the thermal and non-thermal components in the most active regions of a merging cluster."

"Both the intricate internal structure of radio relics and the direct discovery of magnetic draping around the merging bullet are striking illustrations of the non-trivial magnetic features of the intracluster medium. MeerKAT will revolutionise the study of these complex phenomena due to its sensitivity to polarised radiation."

Reference