Oldest ‘Dead’ Galaxy Ever Observed Challenges Understanding of Early Universe
Astronomers using the James Webb Space Telescope (JWST) have made an extraordinary discovery that is challenging our understanding of the early universe. They have found the oldest ‘dead’ galaxy ever observed, a galaxy that ceased forming new stars over 13 billion years ago. This groundbreaking finding raises questions about early galaxy evolution and offers a unique opportunity to study the mechanisms behind galaxy quenching.
The research, led by Tobias J. Looser and an international team of astronomers, was published in the prestigious journal Nature. The study provides fascinating insights into the early universe, contradicting existing models of galaxy evolution. It also challenges the notion that the earliest galaxies were long-living monsters fueled by the remnants of the Big Bang.
The galaxy in question, named JADES-GS-z7-01-QU, existed a mere 700 million years after the Big Bang. It was initially identified as a Lyman break galaxy, a type of galaxy where intense ultraviolet radiation from young, hot stars is absorbed by neutral hydrogen in intergalactic space, creating a characteristic drop in the galaxy’s spectrum. This drop allows astronomers to estimate the galaxy’s redshift, indicating its distance from Earth and therefore its age. In this case, the galaxy is over 13 billion years old.
What makes this discovery even more intriguing is that the JWST’s Near-Infrared Spectrograph (NIRSpec) prism confirmed that the galaxy was quiescent or “dead.” Star formation had completely ceased. However, what baffles the team is how young the galaxy was when it stopped forming stars.
According to Tobias Looser, the first author of the paper, the early universe was a highly active phase with abundant gas clouds collapsing to form new stars. Galaxies required a rich supply of gas to fuel star formation, and the early universe provided an “all-you-can-eat buffet.” This particular galaxy experienced a brief but intense period of star formation lasting between 30 and 90 million years. Then, over a period of about 10 million years, star formation abruptly ceased.
While 10 million years may seem long, it is merely a moment in the cosmic timeline. Modern galaxies have significantly longer lifespans, making this ancient ‘dead’ galaxy an anomaly. The researchers were able to estimate the galaxy’s physical properties, such as size and mass, based on dust attenuation and star formation. They concluded that this small cloud-like galaxy lived fast and died hard.
The existence of such a galaxy at such an early stage challenges our current models of galaxy evolution, which are based on the modern universe. Professor Roberto Maiolino, a co-author of the study, suggests that these models may need to be revisited now that we can observe galaxies from much further back in time. Further research is needed to understand why this galaxy did not last as long as more modern galaxies.
One theory proposed by the astronomers is that in the early universe, star creation and death occurred more rapidly due to the condensed energy and matter. This resulted in more supernovae and black holes. As the universe expanded, star formation became more challenging for some galaxies closer to the source of the Big Bang.
Another theory is that this galaxy died but has since come back to life. The researchers are actively searching for other galaxies like this one in the early universe to help them understand why galaxies stop forming new stars. It could be possible that galaxies in the early universe experience periods of ‘death’ followed by bursts of new life. More observations are needed to confirm this hypothesis.
This groundbreaking discovery opens up new avenues for studying the early universe and challenges our current understanding of galaxy evolution. As we continue to explore the cosmos, we may uncover more ancient galaxies that defy our expectations and provide valuable insights into the mysteries of the universe.
MJ Banias is a journalist who covers security and technology. He is the host of The Debrief Weekly Report. You can email MJ at mj@thedebrief.org or follow him on Twitter @mjbanias.
