A paper authored by a South African researcher presents some “exciting and novel results” from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS) and will be published in the Astronomy & Astrophysics journal.

Using the South African Radio Astronomy Observatory’s (Sarao’s) MeerKAT telescope, located in the Karoo region of the Northern Cape province, this first observatory-led survey demonstrates MeerKAT’s exceptional strengths by producing highly detailed and sensitive images of the radio emissions from 115 clusters of galaxies.

The observations, amounting to about 1 000 hours of telescope time, were done in the year following the inauguration of MeerKAT in 2018.

“In those days, we were still characterising our new telescope, while developing further capabilities required by numerous scientists,” says Sarao commissioning and science operations head Dr Sharmila Goedhart, who adds that MeerKAT was already very capable for studies of this sort and that Sarao observed galaxy clusters as needed to fill gaps in the observing schedule.

More than two years of work followed to convert the raw data into radio images, using powerful computers and to perform scientific analysis addressing a variety of topics. This was done by a large team of South African and international experts led by Dr Kenda Knowles of Rhodes University and Sarao.

The force of gravity has filled the expanding universe with objects extending over an astounding range of sizes, from comets that are 10 km across, to clusters of galaxies that can span 10-million light-years.

These galaxy clusters are complex environments, host to thousands of galaxies, magnetic fields and large regions – millions of light-years across – of extremely hot gas, electrons and protons moving close to the speed of light, and dark matter.

Those ‘relativistic’ electrons, spiraling around the magnetic fields, produce the radio emissions that MeerKAT can 'see' with unprecedented sensitivity, opening new horizons for the deeper understanding of these structures.

Thus MeerKAT, particularly when adding information from optical and infrared and X-ray telescopes, is considered to be exceptionally well-suited to studying the interplay between the components that determine the evolution of galaxy clusters – the largest structures in the universe held together by gravity.

The MGCLS paper just accepted for publication presents more than 50 newly discovered patches of emissions, some of which are understood, while others remain a mystery, awaiting advances in humanity’s understanding of the physical behaviour of cluster plasmas.

The MGCLS has produced detailed images of the extremely faint radio sky, while surveying a large volume of space.

“That’s what’s already enabled us to serendipitously discover rare kinds of galaxies, interactions and diffuse features of radio emissions, many of them quite beautiful,” explains Knowles.

A number of additional studies delving more deeply into some of the initial discoveries are already under way by members of the MGCLS team.