NASA's Webb Telescope Reveals Evolution of Disk Galaxies Over 11 Billion Years

Astronomers utilizing archival data from the NASA/ESA/CSA James Webb Space Telescope have made groundbreaking discoveries regarding the structural evolution of disk galaxies. The comprehensive study, which analyzed a statistical sample of 111 edge-on disk galaxies, spans various periods up to 11 billion years ago—approximately 2.8 billion years post-Big Bang. This research is pivotal in understanding how galaxies form distinct thin and thick disks, a topic that has perplexed scientists for decades.

The current investigation sheds light on the formation mechanisms of dual disk structures in present-day galaxies, which often consist of a thick outer disk and a thinner inner disk. For example, the Milky Way's thick disk extends about 3,000 light-years in height, while its thin disk measures roughly 1,000 light-years. Dr. Takafumi Tsukui, an astronomer at the Australian National University and lead author of the study published in the Monthly Notices of the Royal Astronomical Society, emphasized the significance of their findings, stating, "Our unique measurement of the thickness of the disks at high redshift serves as a benchmark for theoretical study that was only possible with Webb."

According to Dr. Tsukui, the Webb Telescope's advanced resolution capabilities allowed researchers to identify and measure the thickness of these disks distinctly. The results indicate that galaxy formation begins with a thick disk, followed by the emergence of a thin disk. However, the timing of this transition varies based on the galaxy's mass. High-mass galaxies transitioned to two-disk structures approximately 8 billion years ago, whereas low-mass galaxies did so around 4 billion years ago.

Dr. Emily Wisnioski, also from the Australian National University, remarked, "This study is the first to resolve thin stellar disks at higher redshift. Discovering thin stellar disks in place 8 billion years ago, or even earlier, was unexpected."

To further understand these transitions, researchers expanded their analysis to include data from the Atacama Large Millimeter/submillimeter Array (ALMA) and other ground-based surveys. They discovered that the results align with the 'turbulent gas disk' scenario, which posits that turbulent gas in the early Universe triggers intense star formation, leading to the development of a thick stellar disk. As this disk stabilizes, it becomes thinner, resulting in the formation of a thin disk.

The implications of this research extend beyond mere observations. By understanding the structural evolution of disk galaxies, astronomers can refine their models of galaxy formation and address fundamental questions regarding the Universe's history. Dr. Tsukui expressed a desire to enhance their research further, stating, "We aim to incorporate data regarding stellar motion, age, and metallicity, which will allow us to bridge insights from nearby galaxies and those from the early Universe."

As the Webb Telescope continues to provide unprecedented views of the cosmos, the ongoing exploration of galactic structures will likely yield further revelations about the formation and evolution of galaxies, enhancing our comprehension of the Universe itself. This study marks a significant step in that direction, revealing the intricate processes that have shaped the galaxies we observe today.