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Discovery of two new giant radio galaxies offers fresh insights into the universe

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    Science & Technology
  • Published
    22nd Jan, 2021

Two giant radio galaxies have been discovered with South Africa’s powerful MeerKAT telescope located in the Karoo region, a semi-arid area in the south-west of the country.

The galaxy in question

  • The giant radio galaxies were spotted in new radio maps of the sky created by one of the most advanced surveys of distant galaxies.
  • The galaxies in question are several billion light years away. 

What are Radio galaxies?

  • Radio galaxies are driven by non-thermal emission.
  • Radio galaxies get their name from the fact that they release huge beams, or ‘jets’, of radio light.
  • These happen through the interaction between charged particles and strong magnetic fields related to supermassive black holes at the galaxies’ hearts.
  • Radio galaxies differ from normal galaxies in that they emit more radio waves. And because charged particles interact with the strong magnetic fields near the black hole at its centre, jets of radio “light” are released.
  • These tell-tale jets can be many times larger than the galaxy itself, and help identify the presence of a radio galaxy.   

The Survey

  • The team working on the survey has included astronomers from around the world including South Africa, the UK, Italy and Australia.
  • Called the International Gigahertz Tiered Extragalactic Exploration (Mightee) survey, it involves data collected by South Africa’s impressive MeerKAT radio telescope.
    • MeerKAT consists of 64 antennae and dishes and started collecting science datain early 2018.
  • It will ultimately be incorporated into the Square Kilometre Array, an intergovernmental radio telescope project spearheaded by Australia and South Africa.

Significance of the discovery

  • The discovery of enormous jets and lobes in the MIGHTEE map allowed scientists to confidently identify the objects as giant radio galaxies.
  • Their discovery means that a clearer understanding of the evolutionary pathways of galaxies is beginning to emerge. This is tantalising evidence that a large population of faint, very extended giant radio galaxies may exist.
  • This may help scientists understand how radio galaxies become so huge and what sort of havoc supermassive black holes can wreak on their galaxies.

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