Astrophysicists earlier this year found a galaxy located about 3 billion light years away, Alcyoneus is a giant radio galaxy 5 megaparsecs in space. With a diameter of 16.3 million light years, it is the largest known structure of galactic origin.
This discovery sheds light on our misunderstanding of these giants and what drives their incredible growth, according to Science Alert, but it could provide a path to a better understanding, not only of giant radio galaxies, but also of the galactic medium that moves the vast voids of space.
Giant radio galaxies are another mystery in a world full of mysteries. It consists of a host galaxy (the group of stars orbiting the core of a galaxy containing a supermassive black hole), as well as huge jets and lobes emanating from the galaxy’s center.
These jets and lobes interact with the intergalactic medium, acting as a synchrotron to accelerate the electrons that produce radio emission.
And we definitely know what’s producing the jets: an active supermassive black hole at the center of the galaxy. We refer to a black hole as “active” when it consumes (or “accumulates”) material from a giant disk of material that surrounds it.
Not all material in the accretion disk orbiting an active black hole ends up beyond the event horizon. A small part of it is somehow directed from the inner region of the accretion disk to the poles, where it is projected into space in the form of jets of ionized plasma, at speeds exceeding the speed of light.
These jets can travel great distances before expanding into giant lobes that emit radio waves.
This process is very normal. The Milky Way also has radio lobes. What we don’t really have a good idea about is why, in some galaxies, they grow to extremely massive sizes, on megafarsec scales. These are called giant radio galaxies, and the more extreme examples may be key to understanding the drivers of their growth.
“If there are features of host galaxies that are an important reason for the growth of giant radio galaxies, it is likely that they are possessed by the hosts of the largest giant radio galaxies,” the researchers, led by astronomer Martin Owe of the Leiden Observatory in the Countries Bassi, he explained. In their article published in April of this year.
Similarly, if there are some large-scale environments that significantly favor the growth of giant radio galaxies, it is very likely that the largest giant radio galaxies are found in them.”
The team continued to look for these outliers in data collected by Europe’s Low Frequency ARray (LOFAR), an interferometric network of around 20,000 radio antennas, spread across 52 sites across Europe.
They routed the data through a new pipeline, removing embedded radio sources that could interfere with diffuse radio lobe detections, and correcting for optical distortion.
They say the resulting images represent the most sensitive search ever conducted for the galactic lobes. Next, they used the best pattern recognition tool available to locate their target: their eyes.
And that’s how they found Alcyoneus, emanating from a galaxy a few billion light-years away.
“We have detected what is projected to be the largest known structure created by a single galaxy: a gigantic radio galaxy of adequate length predicted [بـ] 4.99 ± 0.04 megaparsecs. The true correct length is at least… 5.04 ± 0.05 megaparsecs,” they explain.
Once the lobes were measured, the researchers used the Sloan Digital Sky Survey to try to understand the host galaxy.
They found that it is a fairly ordinary elliptical galaxy, embedded in the filaments of the cosmic web, with a mass of about 240 billion times the mass of the Sun, with a supermassive black hole of about 400 million times the mass of the Sun at its center .
And both of these parameters are actually at a lower bound for giant radio galaxies, which could provide some clues about what drives the growth of radio lobes.
“Geometry aside, Alcyoneus and its host are suspiciously ordinary: the total low-frequency luminosity intensity, stellar mass, and supermassive black hole mass are less than those of medial giant radio galaxies, despite their similarity,” they write. researchers. central galaxies or black holes are not necessary for the development of large giants, and if the observed condition represents the source for its entire life, then there is also no high radio energy.”
And Alcyoneus may be in a less dense than average region of space, which could allow it to expand — or that interaction with the cosmic web plays a role in the object’s growth.
Whatever is behind it, researchers believe Alcyoneus is still getting bigger the farther out into the cosmic darkness.
The research was published in the journal Astronomy & Astrophysics.
