A research team, including a UC Riverside astronomer, made a discovery using the 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 Way which has been observed to date.
Until now, it was thought that barred spiral galaxies like the Milky Way could not be observed until the universe, estimated to be 13.8 billion years old, reached half its current age.
The research, published in the journal Nature this week, was conducted by scientists from the Centro de Astrobiología in Spain.
“This galaxy, named ceers-2112, formed shortly after the big Bang“, said co-author de la Vega, a postdoctoral researcher in the Department of Physics and Astronomy. “The discovery of 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 structures similar to those of 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 up of stars within galaxies. Galactic bars are similar to bars in our daily lives, like a candy bar. It is possible to find bars in non-spiral galaxies, he explained, but they are very rare.
“Almost all the bars are found in spiral galaxies,” said de la Vega, who joined UCR last year after earning his doctorate in astronomy at Johns Hopkins University. “The bar in ceers-2112 suggests that galaxies matured and became ordered much more quickly than we previously thought, meaning that some aspects of our theories about galaxy formation and evolution need to be revised.”
Astronomers’ previous understanding of galaxy evolution was that it took several billion years for galaxies to be ordered enough to develop bars.
“The discovery of ceers-2112 shows that this can happen in just a fraction of that time, in about a billion years or less,” de la Vega said.
He said galactic bars are thought to form in spiral galaxies with stars rotating in an orderly fashion, as they do in the Milky Way.
“In such galaxies, bars can form spontaneously due to instabilities in the spiral structure or gravitational effects of 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 the galaxies of the early universe.
Implications and contributions of the discovery
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 the fact that some galaxies become stable enough to host bars very early in the history of the universe,” de la Vega said. “These models may need to adjust the amount of dark matter that makes up galaxies in the early universe, because dark matter is thought to affect the rate at which bars form. Second, the discovery of ceers-2112 demonstrates that structures such as bars can be detected when the universe was very young. This is important because galaxies in the past were smaller than they are today, making finding bars more difficult. The discovery of ceers-2112 paves the way for the discovery of other bars 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 in time it is seen, which is a consequence of the finite speed of light,” he said. .
What surprised de la Vega the most in the discovery of ceers-2112 was the ability to limit the properties of its bar.
“I initially thought that detecting and estimating the 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, as well as visits to local schools to give presentations on astronomy. He also leads the Cosmic Thursdays astronomy public discussion series as well as one-off events for special occasions, such as eclipse viewing evenings.
The research paper is titled “A barred spiral galaxy similar to the Milky Way with a redshift of 3.”
Reference: “A barred spiral galaxy similar to the Milky Way 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, MC 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 LY Aaron Yung, 8 November 2023, Nature.