The James Webb Space Telescope found that galaxies formed within 1.5 billion years after the Big Bang were turbulent and clumpy. Studying over 250 young systems, scientists saw chaotic gas flows and intense starbursts that later cooled, transforming these early galaxies into today’s stable spirals.
JWST reveals early galaxies were chaotic clouds that evolved into stable disks
Photo Credit: NASA, ESA, CSA, STScI, B. Robertson
According to new findings by the James Webb Space Telescope (JWST), the first galaxies were much more messy compared to the ones we have today. An analysis of more than 250 systems by researchers at the University of Cambridge, 0.8-1.5 billion years after the Big Bang, revealed the majority of them to be turbulent, clumpy - not the smooth rotating discs of the present day galaxies. During this era, turbulence is caused by the gravitational action and creation of stars, and thus, galaxies found it difficult to settle. The results indicate that these galaxies became cooler over time.
In the study, JWST's infrared cameras traced the motion of ionised hydrogen gas. Almost all the galaxies appeared "still chaotic, with gas puffed up and moving in all directions", as lead author Dr Lola Danhaive notes. Only a few show signs of settling into smooth rotation. Earlier surveys had spotted a few well-ordered disks, but by examining hundreds of smaller galaxies the team finds that most early systems grew via "frequent mergers and bursts of star formation".
As star formation slowed and gas reservoirs were used up, galaxies gradually stabilised. The data span the epoch of reionisation through to the later "cosmic noon" of peak star formation, demonstrating how galaxies evolved "from chaotic clumps into ordered structures". Danhaive notes that early on strong starbursts "disrupt the ordered motions" of a galaxy's gas, whereas later on "galaxies grow their mass and become more stable". In other words, the infant galaxies eventually matured into the graceful spiral galaxies we see today.
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