Abell 523: largest polarized radio emission discovered

INAF (National Institute of Astrophysics) and a team of scientists have developed a polarized signal: in the intergalactic gas of the galaxy cluster Abell 523. It has an expansion at scales 80 times larger than the Milky Way. This signal indicates the presence of a weak but extensive magnetic field with respect to the cluster.

What are clusters of galaxies? These are the largest objects in the universe, including:
hundreds or thousands of galaxies. Such objects are held together by gravity. Clusters of galaxies are
also studied in radio wavelengths. A radio wave sometimes reveals a diffuse emission
conclusive proof of the presence of a particulate gas. The gas moves at similar speeds
to that of the light. There is also a magnetic field in the vast space that divides the forming galaxies
part of the cluster.

When the magnetic field being is structured on a very large scale Radio signal picked up on Earth can detect its polarization. It also provides information about the degree of order of the galaxy cluster’s magnetic field. All this allows us to better study cosmic magnetism.

So the team with INAF turned their attention to the galaxy cluster Abell 523. It is a cluster visible to the naked eye 1.6 billion light-years from the solar system. The field of view made it possible to identify a polarized emission equivalent to 80 galaxies such as the Milky Way.

Thanks to the Very Large Array (VLA), we were able to observe the polarized emission associated with the intergalactic medium of the Abell 523 cluster and shed light on an otherwise inaccessible phenomenon. The polarized emission we have discovered extends over spatial scales in which the total intensity is not actually visible.

Valentina Vacca, researcher at INAF of Cagliari and lead author of the study