Astronomers confirm earliest Milky Way-like galaxy in the universe, just 2 billion years after the Big Bang
Scientists continue to push the boundaries of 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 earliest galaxies in the Universe. In turn, this has led to refined theories and timelines of galactic formation and evolution.
According to the Hubble Sequence, galaxies are grouped into elliptical, spiral, and lenticular based on their morphological characteristics. Whereas galaxies generally begin as irregular disks, they evolve to form spiral arms extending from a central bulge (aka. a spiral galaxy).
Barred spirals, such as the Milky Way, also have a bar-shaped linear arrangement of stars across their centers, which play an important role in their evolution by funneling gas inward from the outer reaches, feeding the supermassive black hole in the center, and suppressing star formation throughout the stellar disk.
While researchers have reported barred spiral galaxies that are even older, analyses of these candidates have been less conclusive, as the observations were made using gravitational lensing or redshift measurements. Whereas the former method is hampered by the lensing effect, which often blurs the light from the more distant object, redshift measurements are subject to errors and uncertainties of 10-15%. Neither method is as definitive as spectroscopy, which was used to validate the age of COSMOS-74706.
The discovery of a barred spiral galaxy this early in the Universe was not entirely surprising, as some simulations suggest that bars were forming in galaxies as far back as 12.5 billion years. However, observational evidence of such structures has been much harder to come by, making this a significant discovery that helps constrain the timeline of galactic evolution. As Ivanov stated in a UPitt press release:
This galaxy was developing bars 2 billion years after the birth of the Universe. Two billion years after the Big Bang. It’s the highest redshift, spectroscopically confirmed, unlensed barred spiral galaxy. In principle, I think that this is not an epoch in which you expect to find many of these objects. It helps to constrain the timescales of bar formation. And it’s just really interesting.
The original version of this article was published on Universe Today.
