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Two cosmic beasts increase knowledge about giant radio galaxies


Two giant radio galaxies have been discovered with the powerful MeerKAT telescope in South Africa, considered among the largest individual objects in the Universe.

While normal radio galaxies are quite common, only a few hundred of them have radio jets that exceed 700 kiloparsecs in size, or about 22 times the size of the Milky Way. These truly huge systems are called “giant radio galaxies.”

Despite the scarcity of giant radio galaxies, the authors found two of these “cosmic beasts” in a remarkably small patch of sky, as posted on Monthly Notices of the Royal Astronomical Society.

Dr. Jacinta Delhaize, a researcher at the University of Cape Town and lead author of the work, said it’s a statement: “We found these giant radio galaxies in a region of the sky that is only about 4 times the area of ​​the full Moon. Based on our current knowledge of the density of giant radio galaxies in the sky, the probability of finding two of them in this region is less than 0.0003 percent. This means that giant radio galaxies are probably much more common than we think! “

Matthew Prescott, a researcher at the University of the Western Cape and a co-author of the work, said in a statement: “These two galaxies are special because they are among the largest known giants and in the top 10% of all giant radii. Galaxies They are more than 2 megaparsecs in diameter, which is equivalent to about 6.5 million light years or about 62 times the size of the Milky Way. However, they are weaker than others of the same size. “

“We suspect that there should be many more galaxies like these, because of the way we think galaxies grow and change throughout their lives.”

Why so few radio galaxies are of such gigantic sizes remains a mystery. Giants are believed to be the oldest radio galaxies, having been around long enough (several hundred million years) for their radio jets to grow outward to these enormous sizes. If this is true, then there should be many more giant radio galaxies than are currently known.

The giant radio galaxies were detected in new radio maps of the sky created by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) study. It is one of the large reconnaissance projects underway with South Africa’s impressive MeerKAT radio telescope, a precursor to the Square Kilometer Array (SKA), which should be fully operational by the mid-2020s.

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