11 billion years old rare ring galaxy – Cosmic Ring of Fire

Astronomers have captured an image of a rare type of galaxy that existed 11 billion years ago. known as the Cosmic Ring of Fire.

A rare circular galaxy with a hole in its center roughly the size of our Milky Way has been found, the discovery was published in Nature Astronomy journal, and is set to shake up theories about the earliest formation and evolution of galaxies.

According to a lead researcher, Tiantian Yuan, from Australia’s ARC Centre of Excellence (ASTRO 3-D) – “it is a very unique object that we have discovered, a galaxy that we’ve never seen before, it looks strange and familiar at the same time.”

“It is making stars at a rate 50 times greater than the Milky Way,” said Dr. Yuan. “Most of that activity is taking place on its ring—so it truly is a “cosmic ring of fire.”

Super rare galaxy – R5519

The galaxy, named R5519, is 11 billion light-years from our Solar System. The hole at its center is enormous, with a diameter 2 billion times longer than the distance between the Earth and our Sun. To put it another way, the R5519 galaxy is 3 million times larger than the diameter of the supermassive black hole in the supermassive galaxy Messier 87, which in 2019 became the first ever to be directly imaged.

Working with researchers from USA, Australia, Denmark, Canada, and Belgium, Dr. Yuan used spectroscopic data acquired from the WM Keck Observatory in Hawaii and images recorded by NASA’s Hubble Space Telescope to identify the rare galaxy. As per the evidence and study conducted by the scientists, the R5519 is a “collisional ring galaxy”, which makes it the first one to be located in the early Universe.

There are two kinds of ring galaxies – collisional type and internally created type. The more common type of ring galaxies originate due to their internal processes. Meanwhile collisional galaxies form as a result of immense and violent encounters with other galaxies in the universe. These collisional type ring galaxies are 1000 times rarer than internally created type. The captured image for R5519 galaxy stems from 10.8 billion years, 3 billion years after the Big Bang, which shows that collisional type ring galaxies have always been rare.

Ring Galaxy
A composite image of the R5519 compiled from single-colour images taken by the Hubble Space Telescope
Image Credit: Tiantian Yuan/Hubble Space Telescope 

Dr. Ahmed Elagali, a co-author of the study said studying R5519 would help determine when and how spiral galaxies originated in our universe. “Further, constraining the number density of ring galaxies through cosmic time can also be used to put constraints on the assembly and evolution of local-like galaxy groups,” he added.

Professor Kenneth Freeman, another co-author of the study from the Australian National University, said the discovery of R5519 had implications for understanding how galaxies like the Milky Way developed. “The collisional formation of ring galaxies requires a thin disk to be present in the victim galaxy before the collision is about to happen,” he explained. The thin disk is the defining aspect of spiral type galaxies: before it assembled, the galaxies were in a disorderly state, not yet recognizable as spiral galaxies.”

“In the case of R5519, we are looking back in time (11 billion years in the past) at the early universe, a time when thin disks were only just assembling. In contrast, the thin disk of our Milky Way began to aggregate only about 9 billion years ago. This discovery is an proof that disk assembly in spiral galaxies occurred over a more extended period than previously thought.”

Read: A strange dwarf planet Ceres & its astrobiological significance


Astronomers see ‘cosmic ring of fire’, 11 billion years ago


A giant galaxy in the young Universe with a massive ring
Nature Astronomy


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