Chethma De Mel, Jadetimes Staff
C. J. De Mel is a Jadetimes news reporter covering Entertainment News
For the first time, in the history of astronomy, it has been observed that one early universe galaxy is being built from inside out with the help of NASA/ESA James Webb Space Telescope. The galaxy looks exactly as it was just 700 million years after the Big Bang. It opens a new frontier in understanding how galaxies have evolved over those 13 billion years by giving a glimpse into the process of early universe galactic formation.
It is indeed remarkably mature for its size, a galaxy one hundred times smaller than the Milky Way. Resembling a metropolis, it consists of a tightly packed starry core central region surrounded by more diffused outer ones. Its outskirts are where the most vigorous star birth activity can be seen, thus hinting at unusual evolution in which the galaxy-wide expansion is driven from inside out. This is the first-ever detection of such inside-out growth, which at the time of Webb's revolutionary observations was only a hypothesis.
The research team at the University of Cambridge studied similar galaxies and used computer models to predict just what the JWST might see. In this way, the study opens up new doors to understanding how galaxies evolved in the early Universe. "The study, published today in Nature Astronomy, shines a light on the formation of early galaxies as they transitioned from simple gas clouds into the complex structures we see today.
Co-lead author Dr Sandro Tacchella of Cambridge's Cavendish Laboratory explained the importance of the finding: "Webb's capability to obtain spectra from the first billion years is opening questions that completely hadn't been considered before about the formation of galaxies. Until now, astronomers had mainly studied the evolution of galaxies over the past 10 million years. With Webb, we can now go back in time and see what happened within the first billion years of the Universe.
Galaxies today grow in two major ways: accreting gas to form new stars, or merging with smaller galaxies. But how early galaxies grew remains an open question that astronomers hope to answer using Webb. The galaxy being observed fits the first scenario in the process of its core being filled with dense star formation as gas falls into it and collapses under gravity. Just as a figure skater pulls their arms in to pick up momentum while spinning, the outer parts of this galaxy balloon out as star formation ramps up.
The galaxy is seen part of the JWST Advanced Extragalactic Survey-or JADES-collectively; it is highly active in stellar creation within the core, with further star creation relegated to its outer regions. While the core is young in age, it is as dense as present-day elliptical galaxies, and the star formation occurring in the outer parts is spreading out to add to the rapid growth of the galaxy. In fact, its outer parts roughly double their stellar mass every 10 million years, while the Milky Way takes 10 billion years to accomplish the same increase.
One of the key breakthroughs of this research lies in the fact that Webb was able to confirm theoretical models of galaxy growth through direct observation. "Webb allows us to verify the things we predict from those earlier simulations, which gives us a deeper knowledge of galactic evolution mechanics," said co-author William Baker, a PhD student at the Cavendish.
Thus, by analyzing the light from the galaxy at a variety of different wavelengths, the team made estimates of stellar age, stellar mass, and star formation rate. Based on their findings, the central part of the galaxy contains older stars, while the disc around it has an intense star-forming activity. The fast growth accompanied by star creation attests to the fact that the gas-rich young galaxy is ready for further star formation processes.
As Tacchella pointed out, this is only one galaxy. To make more general conclusions about how galaxies formed in the early universe, much more work needs to be done. In this way, astronomers can piece together the complete story of just how galaxies like the Milky Way reached their current size and complexity by tracing the history of similar galaxies.
