SA’s MeerKAT radio telescope makes new discovery

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MeerKAT radio data are represented in red/orange hues in this composite view. (Source: SARAO)
MeerKAT radio data are represented in red/orange hues in this composite view. (Source: SARAO)

A new study using the MeerKAT radio telescope has produced a striking image showing a combination of cosmic features never before seen, revealing unexpected details of the inner workings of enormous radio galaxies. 

In a statement today, the South African Radio Astronomy Observatory (SARAO) says at the centre of the giant elliptical galaxy IC 4296 is a rotating black hole with a mass of a billion suns.

It notes that energy released by matter falling onto the black hole generates two opposing radio jets containing magnetic fields and relativistic electrons.

After travelling through intergalactic space at the speed of light for 160 million years, SARAO says, these radio waves were detected by the MeerKAT telescope, located in the Karoo region of the Northern Cape province of South Africa.

Launched in 2018, the South African MeerKAT radio telescope is a precursor to the Square Kilometre Array (SKA), which aims to answer fundamental astrophysical questions about the nature of objects in the Universe.

According to SARAO, construction of the highly-anticipated trans-continental SKA telescope is due to commence in SA and Australia in 2021 and continue until 2027. Science commissioning observations could begin as early as 2023, it notes.

On the new discovery, the organisation says the bright spines of the initially straight jets become unstable just outside the galaxy, where some of the electrons escape to create several faint radio “threads” below IC 4296.

It explains that between the bright jets and the outer lobes are smooth “ribbons” filling channels excavated from the surrounding gas by defunct jets from an earlier period of activity.

The ribbons are eventually stopped by intergalactic gas, nearly a million light-years from the central galaxy (a distance equal to 10 times the diameter of our Milky Way home galaxy), and form the “smoke rings” visible in the left radio lobe, SARAO notes.

Jim Condon of the US National Radio Astronomy Observatory – lead author of the study just accepted for publication in the Astrophysical Journal that summarises this research done by a US-South African team – says “only MeerKAT’s unique combination of sensitivity, angular resolution and dynamic range allowed the discovery of these threads, ribbons and rings” in this previously well-studied galaxy.

As noted by the anonymous reviewer of the manuscript submitted for publication, “it is clear that new results like this from MeerKAT and other SKA pathfinders are set to overhaul our understanding of extragalactic radio sources”.

In January, two giant radio galaxies were discovered by the powerful MeerKAT telescope. These galaxies are among the largest single objects in the universe and are thought to be quite rare.

Last year, a team of astronomers from SA and the US used the MeerKAT telescope to solve a longstanding puzzle in ‘X’-shaped radio galaxies.

In the same year, an international team of astronomers uncovered unusual features in the radio galaxy ESO 137-006 using MeerKAT data.

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