Wednesday, January 4, 2023

Astronomers have recorded the largest shock wave in the universe – it is 60 times larger than the Milky Way

Astronomers managed to get a clear picture of the universe's largest shock wave in the radio range. The wave, whose length is about 60 times greater than the Milky Way, has been traveling through space at a speed close to that of light for 200 million years. According to scientists, it arose as a result of the collision of two galaxy clusters. Details of this study were published in the journal Astronomy & Astrophysics.

The aforementioned study by astronomers is associated with the object Abell 3667, which is located at a distance of about 730 million light years from Earth and is a cluster of galaxies. In fact, Abell 3667 consists of two clusters of galaxies that collided with each other. In total, more than 550 individual galaxies are involved in this process, which slowly “mix” and turn into a huge cosmic “plate”. This is not visible in most telescopes, but as a result of the collision of galaxy clusters, a strong perturbation has arisen - a giant shock wave that comes out from both sides of the merging galaxy cluster and is visible only in the radio range.

As part of the aforementioned study, scientists used the MeerKAT radio telescope located in the Republic of South Africa. With its help, astronomers imaged both halves of the radio component of the shock wave and also discovered that these structures have a much more complex structure than was assumed based on previous observations.

“Shock waves act like giant particle accelerators and accelerate electrons to the speed of light. The waves are streaked with a complex pattern of glowing filaments that help to trace the location of giant magnetic field lines and regions where electrons accelerate.”

According to the researchers, the shock wave appeared about 1 billion years ago, when the collision of the clusters of galaxies that make up Abell 3667 began. The clusters of galaxies are the largest gravitationally bound structures in the Universe. When two of these objects merge, so much energy is released that has not been seen since the Big Bang.

When the wave shot electrons into space at close to the speed of light, the particles destroyed magnetic fields in that region of the universe, emitting arcs of radio waves that scientists can observe today. According to the researchers, these arcs are moving at a speed of about 5.3 million km/s and are located at a distance of about 13 million light years from each other. At the same time, the length of each wave is 60 times greater than the Milky Way, whose diameter is about 100 thousand light years.

Image source: Francesco de Gasperin / SARAO

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