Before 2022 draws to a close, it is worth looking back at the discovery of a massive galaxy last April to end the year with a cosmic blast!
The discovery is called Alcyoneus, which is a gigantic radio galaxy that is around 3 billion light-years away and extends 5 megaparsecs into space. With a length of 16.3 million light-years, it is the longest structure of known galactic origin, as per Science Alert.
Greatest Structures
The greatest structures built by individual galaxies in the universe are giant radio galaxies. They have cosmological lengths and are composed of active galactic nucleus ejecta that emit synchrotron radiation.
However, the primary mechanisms underlying their remarkable growth are still poorly understood by astronomers.
But understanding what propels the growth of these galaxies may depend on looking at their most extreme examples, according to a team of astronomers who discovered the massive galaxy.
The team was led by astronomer Martijn Oei of Leiden Observatory in the Netherlands. They wrote in their paper that the hosts of the greatest giant radio galaxies might contain characteristics that would point to the cause of their growth.
The group searched for these outliers in data gathered by the LOw Frequency ARray (LOFAR) across Europe. An interferometric network made up of over 20,000 radio antennas dispersed across 52 locations throughout the continent.
They claim that the resulting photos constitute the most sensitive search for radio galaxy lobes ever carried out. They then employed the best pattern-finding device at their disposal to find their target with their own eyes.
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The Discovery of Alcyoneus
They discovered Alcyoneus in this manner, erupting from a galaxy a few billion light-years away.
"We have discovered what is in projection the largest known structure made by a single galaxy - a giant radio galaxy with a projected proper length [of] 4.99 ± 0.04 megaparsecs. The true proper length is at least ... 5.04 ± 0.05 megaparsecs," the researchers wrote.
Following the measurement of the lobes, the team used the Sloan Digital Sky Survey to examine the host galaxy.
The galaxy, which weighs around 240 billion times as much as the Sun and has a supermassive black hole at its heart that is about 400 million times the size of the Sun, was discovered to be a typical elliptical galaxy buried in a thread of the cosmic web.
As a result, great radio power and extremely big galaxies or black holes are not required to grow enormous giants if the observed condition indicates the source during its lifetime.
But whatever is causing it, the astronomers are confident that Alcyoneus is still expanding in the cosmic darkness, thousands of light-years away.
The results of the study were further discussed in Astronomy & Astrophysics.
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