Astronomers discover the largest galaxy known to date

Abdul Ghani

With the help of the European radio interferometer, astronomers have discovered a huge radio galaxy. Is that the last beast in the sky? Astronomers have discovered what they claim to be the largest structure of galactic origin.

"We have discovered the largest known structure formed by a single galaxy," writes the team led by Dutch astronomer Martijn Oei in an essay. It is available as a preprint on the Arxiv document server and has already been accepted for publication in the journal Astronomy & Astrophysics.
Radio galaxy (icon image): Alcyoneus is huge, but otherwise "suspiciously ordinary".Image: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble

Alcyoneus is a radio galaxy-spanning 5 megaparsecs or 16.3 million light-years — for comparison, our Milky Way is 170,000 to 200,000 light-years across. The galaxy is about 3 billion light-years away from us.

Jets emanate from the core of the galaxy

Radio galaxies consist of an active galactic core with a supermassive black hole at its center. Two mostly symmetrically arranged emission areas, so-called radio lobes, emanate from it. These lobes, which are much larger than the galaxy's visible core, may be connected to it by rays of matter called jets.

The black hole at the core of a radio galaxy is its source of energy. It pulls almost all of the material from the surrounding accretion disk into itself. A small remnant, however, is ejected into space as jets of ionized plasma at nearly the speed of light. These jets can travel enormous distances before propagating into giant radio lobes called lobes. The interaction between jets and lobes with the intergalactic medium, i.e. with hydrogen, produces radio radiation.

Aside from its extent, Alcyoneus is "suspiciously ordinary," the team writes its mass, around 240 billion times that of the Sun, as well as that of the black hole, which is around 400 million times the mass of the Sun, as well as total low-frequency luminance, are all lower than those of intermediate radio galaxies, which Alcyoneus resembles. A possible explanation could be that Alcyoneus is located in a region with a comparatively low density, which could allow for this expansion.

Alcyoneus was discovered using the radio interferometer Low-Frequency Array (Lofar). This is an array of many radio telescopes whose signals are combined into a single signal. Lofar consists of around 20,000 radio antennas spread over 52 locations in Europe.

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Member Of Freelancers Union (USA), Freelance Writer!, and Digital Creator. Ghani Mengal is an enthusiast Freelance blogger and digital marketer. His content has been published and featured on many popular blogs, websites, and publications. Including TeelFeed,, Data-Driven Investor, TextSniper, Scientific Publication The Predict, The Startup, The Ascent, Heart Affairs, Illumination, And The List goes on.


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