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Cosmic Surprise: Webb Spots Milky Way’s Twin in Early Universe

Astronomers using the James Webb Space Telescope, have discovered ceers-2112, the most distant barred spiral galaxy observed to date. This challenges prior assumptions about galaxy evolution, showing that galaxies became orderly earlier than previously believed, and may lead to changes in theoretical models of galaxy formation.

Research team, including a UC Riverside astronomer, made discovery using the James Webb Space TelescopeThe James Webb Space Telescope (JWST or Webb) is an orbiting infrared observatory that will complement and extend the discoveries of the Hubble Space Telescope. It covers longer wavelengths of light, with greatly improved sensitivity, allowing it to see inside dust clouds where stars and planetary systems are forming today as well as looking further back in time to observe the first galaxies that formed in the early universe.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>James Webb Space Telescope.

Using the James Webb Space Telescope, an international team, including astronomer Alexander de la Vega of the University of California, Riverside (UCR), has discovered the most distant barred spiral galaxy similar to the Milky WayThe Milky Way is the galaxy that contains our Solar System and is part of the Local Group of galaxies. It is a barred spiral galaxy that contains an estimated 100-400 billion stars and has a diameter between 150,000 and 200,000 light-years. The name "Milky Way" comes from the appearance of the galaxy from Earth as a faint band of light that stretches across the night sky, resembling spilled milk.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>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 the journal Nature this week, was led by scientists at the Centro de Astrobiología in Spain.

“This galaxy, named ceers-2112, formed soon after the Big BangThe Big Bang is the leading cosmological model explaining how the universe as we know it began approximately 13.8 billion years ago.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>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.”

Understanding Galactic Bars

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.”

Spiral Barred Galaxy Ceers-2112

Artistic representation of the spiral barred galaxy ceers-2112, observed in the early universe. The Earth is reflected on an illusive bubble surrounding the galaxy, recalling the connection between the Milky Way and ceers-2112. Credit: Luca Costantin/CAB/CSIC-INTA

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.”

Implications and Contributions of the Discovery

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

Alexander de la Vega

Alexander de la Vega is a postdoctoral researcher at UC Riverside. Credit: Alexander de la Vega, UC Riverside

“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.”

At UCR, de la Vega oversees astronomy outreach. He plans telescope nights on and off campus, and visits to local schools to give presentations on astronomy. He also leads the public astronomy talk series “Cosmic Thursdays” as well as one-off events for special occasions, such as viewing parties for eclipses.

The research paper is titled “A Milky Way-like barred spiral galaxy at a redshift of 3.”

Reference: “A Milky Way-like barred spiral galaxy at a redshift of 3” by Luca Costantin, Pablo G. Pérez-González, Yuchen Guo, Chiara Buttitta, Shardha Jogee, Micaela B. Bagley, Guillermo Barro, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Cristina Cabello, Enrico Maria Corsini, Jairo Méndez-Abreu, Alexander de la Vega, Kartheik G. Iyer, Laura Bisigello, Yingjie Cheng, Lorenzo Morelli, Pablo Arrabal Haro, Fernando Buitrago, M. C. Cooper, Avishai Dekel, Mark Dickinson, Steven L. Finkelstein, Mauro Giavalisco, Benne W. Holwerda, Marc Huertas-Company, Ray A. Lucas, Casey Papovich, Nor Pirzkal, Lise-Marie Seillé, Jesús Vega-Ferrero, Stijn Wuyts and L. Y. Aaron Yung, 8 November 2023, Nature.
DOI: 10.1038/s41586-023-06636-x

Source: SciTechDaily