In Greek mythology, Alcyoneus was one of the greatest , son of Ouranos (heaven) and Gaia (earth), and one of the leaders during the Gigantomachy, the battle between giants and the Olympic gods for supremacy over the universe. It is now also the name of a newly discovered giant radio galaxy at 3 billion from U.S. This “monster” 16.3 million light-years long is the largest galactic structure known to date.
Giant among giants…
Giant radio galaxies are still very mysterious objects. It is made up of a host galaxy as well And the huge lobes that stem from . These jets and lobes, interacting with the intergalactic medium, act like a synchrotron that accelerates Which .
the It doesn’t necessarily end yet : a small portion of it is ‘oriented’ from the inner region of the accretion disk towards the poles, where it is projected into space as batches of ionized plasma at equals a large proportion of . These planes can travel vast distances before spreading out in giant lobes that emit waves . the It has such radiolobes. However, it is not really understood why in some galaxies they reach gigantic sizes of millions of light years.the that surrounds
The most extreme examples of these radio giant galaxies could hold the key to understanding the drivers of their growth. The international team led by Martijn Oei, a doctoral student at the Leiden Observatory (Netherlands), explains in his article that “ If there are features of host galaxies that are an important reason for the growth of giant radio galaxies, then it is likely that hosts of larger giant radio galaxies have them. Likewise, if there are special, large-scale environments that are highly favorable for the growth of giant radio galaxies, then the largest giant radio galaxies are likely to be located there. ».
Then they reprocess the data collected by (Lofar), eliminating built-in radio sources that may interfere with radio lobe detections Optical distortion correction. According to the researchers, the resulting images represent the most sensitive search ever made of the galaxy’s radioactive lobes. Then they used their own To determine their target, Alcyonee: We discovered what is predicted to be the largest known structure created by a single galaxy: a giant radio galaxy of the predicted appropriate length. [de] 4.99 ± 0.04 [16,28 ± 0,13 millions d’années-lumière]. The true suitable length is at least 5.04 ± 0.05 megaparsecs [16,44 ± 0,16 millions d’années-lumière] ».
…but it’s a surprisingly typical giant
Then use file researchers found that the host galaxy is Fairly modular, integrated in strands with one A stellar mass is about 240 billion times the mass (4 to 5 times the mass for all of the Milky Way) and a supermassive black hole at its center about 400 million solar masses (about 100 times the mass the supermassive black hole at the center of the Milky Way).
« Geometry aside, Alcyonée and its host are surprisingly ordinary: the overall density ofFew The stellar mass and the mass of the supermassive black hole are all lower, albeit similar, than that of intermediate radio giant galaxies. Thus, very massive galaxies or central black holes are not necessary to produce large quantities [radiogalaxies] Giants, and if the observed case is representative of the source in that Life, high power radio is not ».
It could be that Alcyoneus is in a region of space with a lower-than-average density, which allows it to expand, or the interaction with the cosmic web plays a role in the growth of the body. Regardless, however, researchers believe that Alcyonée continues to grow in size.
What to remember
- The largest galaxy ever has been discovered 3 billion light years from Earth.
- This giant radio galaxy, called Alcyonea, is 16.3 million light-years across.
- This discovery sheds light on our poor knowledge of this giant and what drives its astonishing growth, but it could provide a path to a better understanding, not only of giant radio galaxies, but also of the galactic medium.
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