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Ancient 'ring of fire' galaxy found glaring at Earth across space and time

Eleven billion years ago, a hot, active, galaxy that looked like an eye glared across space. Now, using data from the W.M. Keck Observatory in Hawaii and the Hubble Space Telescope, astronomers have captured a snapshot of its unblinking gaze.

This galaxy, R5519, is made up of a flat ring of stars, with a hole in the middle where astronomers believe another blob of stars punched through. Galaxies like this, known as "collisional ring galaxies," turn up infrequently in the modern universe. But this is the first time astronomers have seen one so old and far away; at 11 billion light-years from our planet, its ancient light is only just reaching Earth.

An animation illustrates the process that might have formed the hole at the galaxy's center. (Image credit: James Josephides, Swinburne Astronomy Productions)

Related: The 15 weirdest galaxies in our universe

Galaxies in the early universe tended to be very active, churning up hot gas and turning it into stars. R5519 is no exception, the researchers said in a statement.

"It is making stars at a rate 50 times greater than the Milky Way," Tiantian Yuan, an astronomer at Australia's Swinburne University of Technology and lead discoverer of the galaxy, said in the statement. "Most of that activity is taking place on its ring – so it truly is a ring of fire."

Most of the ring-shaped galaxies in our universe form through internal processes, the researchers said. Only 1 in 1,000 in the modern universe forms through collisions. Still, according to the new paper, which was published May 25 in the journal Nature Astronomy, this galaxy's shape does appear to be the result of a collision with another object.

A composite image made from multiple single-color Hubble Space Telescope images shows what the galaxy looks like from Earth. (Image credit: Tiantian Yuan/Hubble Space Telescope)

This monumental collision offers clues about the conditions that prevailed during the early universe, the scientists said.

So, how did R5519's unblinking "Eye of Sauron" shape come into being?

For a ring to form, a galaxy like this has to start as a wide, flat disk of stars and gas, the researchers said. One such disk that formed about 9 billion years ago turned into the spiral Milky Way. Another formed Andromeda, a neighboring galaxy.

But R5519's disk, if it indeed existed before another object punched that hole in its center, would have existed a full 2 billion years earlier, just 3 billion years after the Big Bang.

"This discovery is an indication that disk assembly in spiral galaxies occurred over a more extended period than previously thought," Kenneth Freeman, an Australian National University astronomer and co-author of the paper said in the statement.

That changes how astronomers see that early history of the universe.

Originally published on Live Science.

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  • rod
    I note from the nature astronomy link provided in this article two points. From the abstract "Our discovery offers a unique pathway for studying density waves in young galaxies, as well as constraining the cosmic evolution of spiral disks and galaxy groups. The ring galaxy (ID 5519, hereafter R5519) was..."

    Density waves are required to regenerate spiral arms in galaxies, spiral arms have limited lifetimes compared to the age of the universe in the BB model and galaxy ages assigned (perhaps 100-300 million years max). If not regenerated we live in a unique period to see spiral arms today. The other point here, DM is critical to the model calculations and distance interpretation too.

    "Methods Throughout we adopt a Λ cold dark matter cosmology, where is Λ the cosmological constant, with ΩM = 0.307, ΩΛ = 0.693 and H0 = 67.7 km s−1 Mpc−1, consistent with the Planck measurements31 and the cosmological parameters used in EAGLE simulations13. At the redshift of z = 2.19, the look-back time is 10.8 Gyr and 1″ corresponds to a physical scale of 8.49 kpc. All magnitudes are in AB units32, unless otherwise specified."

    The redshift for R5519 is z=2.19.
    Reply