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This image of galaxy cluster Abell 2744, also called Pandora's Cluster, was taken by the Spitzer Space Telescope. NASA/JPL-Caltech

The universe is a big place populated by big things. Galaxy clusters — massive structures formed over millions, or even billions of years, as smaller galaxies move closer due to gravitational attraction — are among the biggest objects in the observable universe.

However, according to a study published Wednesday in the journal Astronomy and Astrophysics, the cosmos may just have something much larger than these ginormous structures. The study, based on observations made using the 100-meter Effelsberg radio telescope in Germany, reveals that collisions between galaxy clusters create massive magnetic fields — many of which may be bigger than the clusters themselves.

“We discovered the so far largest ordered magnetic fields in the universe, extending over 5-6 million light years,” study lead author Maja Kierdorf from the Max Planck Institute of Radio Astronomy said in a statement released Wednesday.

In addition to stars, gas, dust, planets and the omnipresent dark matter, galaxy clusters, which typically extend over a distance of about 10 million light-years, contain charged particles. These charged particles create their own magnetic fields, and when two clusters collide, the shock compression of hot gas and magnetic fields leads to the creation of arc-like features astronomers call “relics.”

One of the galaxy clusters the researchers looked at — CIZA J2242+53 — contains a relic named “Sausage” because of its shape. So far, relics have been found in about 70 galaxy clusters.

galaxy cluster
The relic at the outskirts of the galaxy cluster CIZA J2242+53, named „Sausage“ because of its shape, is located at a distance of about two billion light years from us. The contour lines show the intensity of the radio emission at a wavelength of 3 cm, observed with the 100-m Effelsberg radio telescope. The colors represent the distribution of linearly polarized radio intensity at the chosen wavelength. The short dashes indicate the orientation of the magnetic field. The bright source at the bottom is a radio galaxy that belongs to the same galaxy cluster. M. Kierdorf et al., A&A 600, A18

For the purpose of this study, the astronomers took images of these relics in radio waves using the Effelsberg telescope. Linearly polarized relics — signs of extremely ordered magnetic fields — were found in the four galaxy clusters observed, in one case for the first time. The magnetic fields were of similar strength to the Milky Way’s, and were highly polarized.

Analysis of the degrees of polarization also revealed that galaxy clusters collide with velocities of roughly 2,000 kilometer per second (4.4 million miles per hour) — much higher than previous measurements derived from observations of X-ray emissions.

“Now we can systematically search for ordered magnetic fields in galaxy clusters using polarized radio waves,” study co-author Rainer Beck, also from the Max Planck Institute, said in the statement.

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