Two new ancient galaxies have been discovered

An artistic impression of an ancient galaxy.

An artistic impression of an ancient galaxy.
Picture: University of Copenhagen / NASA

The presence of two previously undiscovered galaxies about 29 billion light-years apart suggests that our understanding of the early universe is disturbingly flawed.

We present REBELS-12-2 and REBELS-29-2 — two galaxies we didn’t even know existed until recently. It took light from these galaxies 13 billion years to get here, because these objects formed soon after the Big Bang. The ongoing expansion of the universe sets these ancient galaxies approximately 29 billion light-years from Earth.

New research published in the journal Nature suggests that REBELS-12-2 and REBELS-29-2 avoided detection up to this point because our view of these galaxies is blurred by thick layers cosmic dust. The Hubble Space Telescope, however powerful, could not peek through the celestial nebula. It took ultra-sensitive ALMA radio telescope in Chile to spot galaxies, in what turned out to be accidental.

“We looked at a sample of very distant galaxies, which we already knew existed from the Hubble Space Telescope. And then we noticed that two of them had a neighbor we didn’t expect to be there at all, ”explained Pascal Oesch, an astronomer at the Cosmic Dawn Center at the Niels Bohr Institute in Copenhagen. statement. “Since both of these neighboring galaxies are surrounded by dust, part of their light is blocked, making them invisible to Hubble.”

Oesch is an expert at finding some of the most distant galaxies in the universe. Back in 2016, he and his colleagues discovered the 13.4 billion-year-old galaxy GN-z11, setting cosmic distance record. GN-z11 was formed only 400 million years after the Big Bang.

The ALMA radio telescope made this discovery possible.

The ALMA radio telescope made this discovery possible.
Picture: University of Copenhagen / NASA

The new paper describes how ALMA and a new observation technique developed by Oesch and colleagues could spot similarly obscured ancient galaxies. And obviously there are many more awaiting discovery. Astronomers compared the two newly discovered galaxies to previously known galactic sources in the early universe, leading them to suspect that “up to one of the five earliest galaxies may have been missing on our map of the sky,” Oesch said.

He added, “Before we can begin to understand when and how galaxies formed in space, we first need proper accounting.” Indeed, the new work claims that there were more ancient galaxies in the early universe than previously believed. This is significant because the earliest galaxies formed the building blocks of later galaxies. So until we have “proper accounting,” as Oesch said, astronomers could work with a flawed or otherwise inaccurate model of the early universe.

The task now will be to find these missing galaxies, and fortunately, the upcoming instrument promises to make this job much easier: the Webb Space Telescope. This next-generation observatory, Oesch said, “will be much more sensitive than Hubble and capable of exploring longer wavelengths, which should allow us to see these hidden galaxies with ease.”

The new work is therefore verifiable, as observations made by Webb are likely to confirm, negate, or further improve the researchers ’predictions. The space telescope is designed for to launch from French Guiana on Wednesday, December 22 7:20 AM ET (4:30 PM).

More: The Webb telescope was not damaged after the installation incident, NASA says.

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Naveen Kumar

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