The biggest galaxy ever seen, known as Alcyoneus, has been discovered, according to a recent study that was published in the journal Astronomy & Astrophysics.
Alcyoneus is an elliptical galaxy that is 160 times bigger than our Milky Way galaxy and is located around 3 billion light-years from Earth. It has a diameter of 16.3 million light-years.
Alcyoneus is a radio galaxy, which means that its supermassive black hole consumes matter and produces two plasma jets that travel at almost the speed of light. After traveling millions of light-years, these jets cooled down and fanned out, generating radio waves that made the galaxy visible to scientists.
While plasma-filled radio lobes are common in galaxies, the magnitude of Alcyoneus’ lobes is unique, making it difficult to understand how it expanded to such extent. When going through data seeking for big, diffuse radio lobes, the researchers analyzed data gathered by the Low-Frequency Array (LOFAR), a network of radio telescopes across Europe. They stumbled onto Alcyoneus by accident.
One theory being considered by experts looking at the probable origins of Alcyoneus’ enormous size is that its surroundings may be less dense than normal, enabling its jets to extend to previously unheard-of sizes. Another theory is that Alcyoneus is located within the cosmic web’s filament, a structure made of gas and dark matter that connects galaxies.
The explanation for why Alcyoneus has grown to such a vast extent, according to the researchers, will provide light on how other galaxies develop. They point out that the biggest giant radio galaxies will probably have them if host galaxy traits are crucial for giant radio galaxy development. The biggest radio galaxies are anticipated to be located in certain large-scale settings that are particularly favorable for gigantic radio galaxy development.
Alcyoneus, despite its enormous size, has a center supermassive black hole that is 100 times less massive than the biggest known black hole and a total mass that is around half that of the Milky Way.
Reference(s): Research Article