Scientists continue to push boundaries astronomy and cosmology, thanks to next-generation instruments that can see farther and clearer than ever before.
Through these efforts, astronomers have observed some of the oldest galaxies in the universe. This in turn has led to improved theories and timelines of galaxy formation and evolution.
According to the Hubble sequence, galaxies are grouped into ellipticals, spirals, and lenticulars based on their morphological properties. While galaxies generally start out as irregular disks, they evolve to form spiral arms extending from the central bulge (also known as a spiral galaxy).
Barred spirals, like the Milky Way, also have a linear, ribbon-shaped arrangement of stars across their centers, which plays an important role in their evolution by directing gas inward from the outer edges, feeding the supermassive black hole at the center, and suppressing star formation throughout the stellar disk.
While researchers have reported the existence of even older barred spiral galaxies, analyzes of these candidates have been less conclusive, as observations were made using gravitational lensing or redshift measurements. While the first method is hampered by the lensing effect, which often blurs light coming from the farthest object, redshift measurements are subject to errors and uncertainties of 10-15%. Neither method is as conclusive as spectroscopy, which was used to verify the age of COSMOS-74706.
The discovery of a barred spiral galaxy in the early universe is not entirely surprising, as some simulations suggest that bars were forming in galaxies as early as 12.5 billion years ago. However, observational evidence for such structures has been much more difficult to obtain, making this an important discovery that helps constrain the timeline of galaxy evolution. As Ivanov mentioned in UPitt press release:
This galaxy was evolving into bars 2 billion years after the birth of the universe. Two billion years after the Big Bang. It is the highest redshift, spectroscopically confirmed, non-lensing spiral galaxy. In principle, I think this is not the age where you would expect to find many of these things. It helps restrict tape formation timelines. This is really interesting.
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