Astronomers discover ‘fossil galaxy’ 3 billion light years away

A galaxy that has remained unchanged for 7 billion years – a rarity in the universe – has been observed by astronomers that have been expanded into a look at the cosmic history and a puzzling collection of objects, which are referred to as relics or “fossil galaxies”.

These space curiosities are galaxies that escape their expected evolutionary path after a first phase of intensive star formation. While other galaxies expand and merge together, the fossil galaxies remain practically inactive. Like heavenly time capsules, they offer a snapshot in the old universe and enable astronomers to examine the mechanism of galaxy formation.

The newly discovered fossil galaxy, which children are called J0842+0059, is about 3 billion light years from the earth. It is therefore both the distance and the first of its kind, which was observed outside the local universe, the region of the area closest to the earth, which is about 1 billion light years on a radius. It was found by a team of astronomers under the direction of the Italian National Institute for Astrophysics (Inaf), with high -resolution imaging from the large binocular telescope in Arizona.

“Relic galaxies did not happen to have merged with another galaxy that remained more or less intact over time,” said Crescenzo Tortora, a researcher at Inaf and the first author of a study on the Royal Astronomical Society published on May 31 in the Malfunger Notices magazine. “These objects are very rare because over time, the likelihood of merging with another galaxy increases naturally.”

Very compact, very solid

Astronomers believe that the most massive galaxies form in two phases, according to the study Coautor Chiara Spiniello, researcher at the University of Oxford in Great Britain.

“Firstly, there is an early outbreak of star formation, a very fast and violent activity,” she said. “In the end we have something very compact and small, the ancestor of this relic.”

The second phase, she added, was a lengthy process in which galaxies that are in the immediate vicinity, interact, work together and eat each other, which leads to a very dramatic change in their forms, sizes and star populations. “We define a relic as an object that almost completely overlooked in this second phase after we had formed at least 75% of its mass in the first phase,” said Spiniello.

The treacherous feature of fossil galaxies is that they are very old, compact and dense, much more than our own galaxy.

“They contain (billions) of stars that are as massive as the sun and they do not form new stars – they essentially do nothing and they are the fossil records of the very old universe,” she said. “They formed when the universe was really, very young. And then for some reasons that we honestly did not understand, they did not interact with each other. They did not merged with other systems. They developed undisturbed and they remained the way they were.”

Fossil galaxies are crucial because they are a direct connection to the massive galaxy population that existed billions of years ago, said Michele Cappellari, professor of astrophysics at the University of Oxford, which was not involved in the study. “As” living fossils “they avoided the chaotic mergers and growth that most other massive galaxies have experienced. Examined we enable us to reconstruct the conditions of the universe in its infancy and to understand the initial outbursts of star development,” he said.

What caused these galaxies to no longer form the stars so abruptly is an important question, he added. “Evidence of both locals and (distant) observations suggest that feedback from super massive black holes can be responsible,” said Cappellari. “These black holes can create powerful winds that drive or heat the gas in a galaxy and prevent further stars. However, this remains an active research area.”

An uncertain future

Scientists identified in 2018 children J0842+0059 in 2018 with the VLT Survey Telescope (VST) at the Paranal Observatory in Chile. This observation showed that the galaxy was populated by very old stars, but only provided an estimate of its mass and size, so that a more detailed observation was required to confirm that it was a relic. The large binocular telescope used for this confirmation can, due to its ability to compensate for atmospheric turbulence that can take very sharp images to concentrate on remote objects.

The newly found fossil galaxy joins a group of only one handful of others who were observed at the same level of detail, the most flawless of which was confirmed in 2018 by the Hubble world space telescope.

NGC 1277 and children J0842+0059 are very similar, but the latter is much further away from the earth. According to Spiniello, it almost perfectly fits the definition of the fossil galaxy.

“We call that an extreme relic,” she said, “because almost all or 99.5% of his stars were formed incredibly early in the cosmic period and the galaxy did nothing afterwards.”

The fossil galaxy has stars and planets, just like our own galaxy, but it is much denser, added Spiniello. “There will be many other stars in a tiny, tiny volume, so it will be great,” she said. “And it will be much more difficult to find solar systems like ours, with many planets around them just because the opportunities to disturb accompanying stars nearby.”

Children J0842+0059 look at observers as if it had done 3 billion years ago, because it takes time for the light to get out of the galaxy to reach the earth. Spiniello put up the hypothesis that the relic will probably remain as it is forever, but scientists cannot be sure because they still don’t know what to prevent from interacting with other galaxies.

“There must be something that prevents her from fusion, but without knowing what, we can’t really predict what will happen in the future,” said Spiniello.

“One in millions”

It is very difficult to identify fossil galaxies and to confirm their nature, partly because, compared to regular galaxies such as the Milky Way, they are relatively rare and small, according to Sébastien Comerón, an extra -alactic astronomer at the Universidad de la Laguna and the Instituto de Astrofísica de Canarien in Spain in Spain. The confirmation of a distant relic galaxy is a credit for the search strategies used to identify these objects and modern instruments, he said.

“Relic galaxies are mysterious,” added Comerón, who was not involved in the study, in an e -mail. “The fact that some galaxies are now untouched relics of the first major galaxies must be explained.”

Astronomers cannot certainly say how rare relics are, but Spiniello estimates that there are “one in millions” among all galaxies in the universe. The Inspire Project, which is supposed to find and cataloged fossil galaxies and has produced the discovery of children J0842+0059, has already identified several dozen other candidates who are in the pipeline for further examination, said Spiniello.

New instruments could make this search even more effective. Both Spiniello and Tortora are happy about Euclid, a telescop for the European Space Agency, which started in 2023, with the aim of exploring dark matter and dark energy, which will also be useful for the observation of fossil galaxies.

“Euclid will be transformative,” said Spiniello, “because the configuration of the Wide Sky Survey, instead of observing a single object, covers much more.

The confirmation of Relic Galaxy Kids J0842+0059 at such a distance is a remarkable performance, and the future of this field is very promising, said Cappellari in an e -mail. “With powerful new telescopes such as James Webb and Euclid (which produced his first pictures a few months ago) and expecting on site with advanced adaptive look, we can expect to find and study more of these relics in even larger distances.”

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