Two gigantic radio galaxies have just been discovered thanks to the 64 antennas of the powerful MeerKAT telescope, in South Africa, in the course of an investigation in which some thirty astronomers from institutes and observatories around the world have participated. A radio galaxy is a type of active galaxy that is characterized by its great luminosity in radio frequencies, which emit in the form of large and powerful jets or jets. The jets are formed as a result of the interaction of charged particles and powerful magnetic fields around the supermassive black holes found at the hearts of these galaxies.
The two new radio galaxies, however, stand out above all the others. Indeed, of the millions of radio galaxies found so far only 800 are giants, and the two newly discovered could be the largest single objects observed so far in the entire Universe. Despite its large size, tens of times larger than our Milky Way, this galactic population is difficult to detect as its dim and diffuse light is beyond the reach of most telescopes.
In the words of Jacinta Delhaize, a researcher at the University of Cape Town and lead author of the study just published in Monthly Notices of the Royal Astronomical Society, We found these giant radio galaxies in a region of the sky that is only 4 times the area of the Moon. Based on our current knowledge of the density of giant radio galaxies, the probability of finding two of them in this very small region is less than 0.0003 percent. And that means that giant radio galaxies are probably much more common than usual! what we thought!
BIG AND OLD: THESE ARE TWO RADIO GALAXIES WHOSE DIAMETER IS AROUND 6.5 MILLION LIGHT YEARS AND WHICH COULD BE THE LARGEST INDIVIDUAL OBJECTS SEEN SO FAR IN THE UNIVERSE
The finding provides astronomers with new clues about how galaxies evolve and also unravels the mystery of the enormous size and age of some radio galaxies, which are believed to be among the oldest in the Universe.
The two galaxies in question are several billion light-years distant from us. These two galaxies – explains Matthew Prescott, co-author of the work – are special because they are among the largest known and in the top 10.5% of all giant radio galaxies. They have more than 2 megaparsecs in diameter, which is equivalent to about 6.5 million light-years away, about 62.5 times the size of the Milky Way.
The reason why only a few among the millions of known radio galaxies reach such gigantic sizes remains a mystery. It is believed that the largest is also the oldest, and if that is true, there must be many more than the few hundred that are currently known. According to Delhaize, in the past, this galactic population has been hidden from view by the technical limitations of radio telescopes. But now that population is being revealed thanks to the impressive capabilities of the new generation of instruments.
