Milky Way-like galaxy found in the early universe

Using the James Webb Space Telescope, an international team, including astronomer Alexander de la Vega of the University of California, Riverside, has discovered the most distant barred spiral galaxy similar to the Milky Way that has been observed to date.

Until now it was believed that barred spiral galaxies like the Milky Way could not be observed before the universe, estimated to be 13.8 billion years old, reached half of its current age.

The research, published in Nature this week, was led by scientists at the Centro de Astrobiología in Spain.

"This galaxy, named ceers-2112, formed soon after the Big Bang," said coauthor de la Vega, a postdoctoral researcher in the Department of Physics and Astronomy. "Finding ceers-2112 shows that galaxies in the early universe could be as ordered as the Milky Way. This is surprising because galaxies were much more chaotic in the early universe and very few had similar structures to the Milky Way."

Ceers-2112 has a bar in its center. De la Vega explained that a galactic bar is a structure, made of stars, within galaxies. Galactic bars resemble bars in our everyday lives, such as a candy bar. It is possible to find bars in non-spiral galaxies, he said, but they are very rare.

"Nearly all bars are found in spiral galaxies," said de la Vega, who joined UCR last year after receiving his doctoral degree in astronomy at Johns Hopkins University. "The bar in ceers-2112 suggests that galaxies matured and became ordered much faster than we previously thought, which means some aspects of our theories of galaxy formation and evolution need revision."

Astronomers' previous understanding of galaxy evolution was that it took several billion years for galaxies to become ordered enough to develop bars.

"The discovery of ceers-2112 shows that it can happen in only a fraction of that time, in about one billion years or less," de la Vega said.

According to him, galactic bars are thought to form in spiral galaxies with stars that rotate in an ordered fashion, the way they do in the Milky Way.

"In such galaxies, bars can form spontaneously due to instabilities in the spiral structure or gravitational effects from a neighboring galaxy," de la Vega said. "In the past, when the universe was very young, galaxies were unstable and chaotic. It was thought that bars could not form or last long in galaxies in the early universe."

The discovery of ceers-2112 is expected to change at least two aspects of astronomy.

"First, theoretical models of galaxy formation and evolution will need to account for some galaxies becoming stable enough to host bars very early in the universe's history," de la Vega said. "These models may need to adjust how much dark matter makes up galaxies in the early universe, as dark matter is believed to affect the rate at which bars form. Second, the discovery of ceers-2112 demonstrates that structures like bars can be detected when the universe was very young. This is important because galaxies in the distant past were smaller than they are now, which makes finding bars harder. The discovery of ceers-2112 paves the way for more bars to be discovered in the young universe."

De la Vega helped the research team by estimating the redshift and properties of ceers-2112. He also contributed to the interpretation of the measurements.

"Redshift is an observable property of a galaxy that indicates how far away it is and how far back in time the galaxy is seen, which is a consequence of the finite speed of light," he said.

What surprised de la Vega most about the discovery of ceers-2112 is how well the properties of its bar could be constrained.

"Initially, I thought detecting and estimating properties of bars in galaxies like ceers-2112 would be fraught with measurement uncertainties," he said. "But the power of the James Webb Space Telescope and the expertise of our research team helped us place strong constraints on the size and shape of the bar."

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Astronomers find abundance of Milky Way-like Galaxies in early Universe, rewriting cosmic evolution theories

Galaxies from the early Universe are more like our own Milky Way than previously thought, flipping the entire narrative of how scientists think about structure formation in the Universe, according to new research published today.

Using the James Webb Space Telescope (JWST), an international team of researchers including those at The University of Manchester and University of Victoria in Canada discovered that galaxies like our own Milky Way dominate throughout the universe and are surprisingly common.

These galaxies go far back in the Universe's history with many of these galaxies forming 10 billion years ago or longer.

The Milky Way is a typical 'disk' galaxy, which a shape similar to a pancake or compact disk, rotating about its centre and often containing spiral arms. These galaxies are thought to be the most common in the nearby Universe and might be the types of galaxies where life can develop given the nature of their formation history.

However, astronomers previously considered that these types of galaxies were too fragile to exist in the early Universe when galaxy mergers were more common, destroying what we thought was their delicate shapes.

The new discovery, published today in the Astrophysical Journal, finds that these 'disk' galaxies are ten times more common than what astronomers believed based on previous observations with the Hubble Space Telescope.

Christopher Conselice, Professor of Extragalactic Astronomy at The University of Manchester, said: "Using the Hubble Space Telescope we thought that disk galaxies were almost non-existent until the Universe was about six billion years old, these new JWST results push the time these Milky Way-like galaxies form to almost the beginning of the Universe."

The research completely overturns the existing understanding of how scientists think our Universe evolves, and the scientists say new ideas need to be considered.

Lead author, Leonardo Ferreira from the University of Victoria, said: "For over 30 years it was thought that these disk galaxies were rare in the early Universe due to the common violent encounters that galaxies undergo. The fact that JWST finds so many is another sign of the power of this instrument and that the structures of galaxies form earlier in the Universe, much earlier in fact, than anyone had anticipated. "

It was once thought that disk galaxies such as the Milky Way were relatively rare through cosmic history, and that they only formed after the Universe was already middle aged.

Previously, astronomers using the Hubble Space Telescope believed that galaxies had mostly irregular and peculiar structures that resemble mergers. However, the superior abilities of JWST now allows us to see the true structure of these galaxies for the first time.

The researchers say that this is yet another sign that 'structure' in the Universe forms much quicker than anyone had anticipated.

Professor Conselice continues: "These JWST results show that disk galaxies like our own Milky Way, are the most common type of galaxy in the Universe. This implies that most stars exist and form within these galaxies which is changing our complete understanding of how galaxy formation occurs. These results also suggest important questions about dark matter in the early Universe which we know very little about."

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