SA’s powerful MeerKAT telescope discovers two rare radio galaxies

South Africa’s powerful MeerKAT telescope discovered two giant and rare radio galaxies. The findings will give astronomers vital clues about how galaxies have changed and evolved throughout over time.

“Two giant radio galaxies have been discovered with South Africa’s powerful MeerKAT telescope. These galaxies are amongst the largest single objects in the Universe and are thought to be quite rare”.

South African Radio Astronomy Observatory, Twitter

MeerKAT radio galaxy discovery

Extremely rare

Dr Jacinta Delhaize, a Research Fellow at the University of Cape Town (UCT) – and the lead author of the work – explains:

“Many hundreds of thousands of radio galaxies have already been discovered. However, only around 800 of these have radio jets exceeding 700 kilo-parsecs in size or around 22 times the size of the Milky Way. These truly enormous systems are called ‘giant radio galaxies’.”

Dr Jacinta Delhaize

Delhaize adds that the team of researchers found “these giant radio galaxies in a region of sky which is only about four times the area of the full moon”. The “probability of finding two of them in this region is extremely small”.

meerkat discovery radio galaxies
Part of the MIGHTEE radio map of the sky. A zoom-in of each giant radio galaxy is shown in greyscale. The purple line traces around the radio emission from the giants. Image credit: I. Heywood/Oxford/Rhodes/SARAO

Extremely large

As per a press release published by the South African Radio Astronomy Observatory, the giant radio galaxies were spotted by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey.

Thanks to this discovery, scientists will now have a “clearer understanding of the evolutionary pathways of galaxies is beginning to emerge”. The research was published in the Monthly Notices of the Royal Astronomical Society on 18 January 2021.

It shows that the two radio galaxies discovered by MeerKAT are amongst the largest single objects in the universe. Based on their location, it has also been deducted that they are quite rare.

In addition, co-author of the work Dr Matthew Prescott adds that these newly-discovered galaxies “are much bigger than most other radio galaxies”.

“They are more than 2 Mega-parsecs across which is around 6,5-million light-years or about 62-times the size of the Milky Way. Yet they are fainter than others of the same size. We suspect that many more galaxies like these should exist, because of the way we think galaxies should grow and change over their lifetimes”.

Dr Jacinta Delhaize

Extremely old

Furthermore, Dr Ian Heywood, a co-author at the University of Oxford, explains that the team “found largescale radio jets coming from the central galaxies, as well as fuzzy cloud-like lobes at the ends of the jets”.

It is believed that the giant radio galaxies are the oldest, and may have existed for several hundred million years, in order for their “radio jets to grow outwards to these enormous sizes”.

“We know that these galaxies are several billion light-years away, and so it was the discovery of these jets and lobes in the MIGHTEE map that allowed us to confidently identify the objects as giant radio galaxies”.

Dr Ian Heywood

Other noteworthy MeerKAT discoveries

Back in September 2019, an international team of astronomers, scientists and researchers used MeerKAT to discover ‘balloon-like structures towering hundreds of light-years above and below the centre of the Milky Way.

The ‘towers’, or ‘bubbles’ as some scientists refer to it, were caused by a “phenomenally energetic burst that erupted near the Milky Way’s supermassive black hole a few million years ago”. At the time, Camilo explained:

“Teasing out the bubbles from the background noise was a technical tour de force, only made possible by MeerKAT’s unique characteristics and ideal location”.

In July 2019, an international team of astronomers discovered vast amounts of hydrogen gas in NGC 1316, a galaxy 60 million light-years from Earth, using the MeerKAT telescope. The research into NGC 1316 is funded in part by the European Research Council.

“Galaxy merging is one of the cornerstones of modern cosmological theories. Examples such as NGC 1316 are of great importance because they allow astronomers to study in detail the physical processes at work during mergers; and their effect on galaxy evolution.”

Then in May 2020, a team of astronomers from South Africa used the MeerKAT telescope to solve a longstanding puzzle in X-shaped radio galaxies which are situated far, far away – approximately 800 million light-years from Earth.

The jets of the radio waves stretch for millions of light-years into space; truly a spectacular sight. As they flow back towards the central galaxy, the waves are deflected, and therein lies the mystery.

While “twin jet” galaxies are a common occurrence in the Milky Way, the X-formation is not. Thanks to MeerKAT telescope and the team of researchers, the phenomena can finally be explained. Read more here: SA MeerKAT Telescope solves longstanding ‘X-galaxies’ mystery

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