Galaxy Formation
Galaxy formation is the process by which galaxies assemble and evolve in the universe, beginning shortly after the Big Bang and continuing to the present day. The formation and early development of galaxies remains a central question in cosmology, as observations reveal galaxies existed when the universe was only a few hundred million years old—earlier than many theoretical models predicted. Understanding how these first galaxies formed, what composed them, and how they grew over cosmic time requires both theoretical frameworks and advanced observational data.
Early Universe and Population III Stars
The earliest galaxies are believed to have formed from the gravitational collapse of dark matter halos, which provided the scaffolding for baryonic matter to accumulate. Recent observations by the James Webb Space Telescope (JWST) of the galaxy GN-z11 have provided critical evidence for the presence of Population III stars in the early universe. These hypothetical first-generation stars, composed primarily of hydrogen and helium, are thought to have ignited shortly after the cosmic dark ages ended, initiating the epoch of reionization and enriching the interstellar medium with heavier elements.
Evolution and Structure
As the universe expanded, galaxies underwent hierarchical merging, where smaller structures coalesced to form larger systems. This process drove the morphological evolution of galaxies, leading to the diverse structures observed today, including spirals, ellipticals, and irregulars. The interplay between star formation rates, supernova feedback, and supermassive black hole activity regulated the growth of galactic mass and influenced the chemical enrichment of the cosmic web.
Source Notes
- 2026-04-12: Possible Discovery of First Ever Stars in the Universe
- 2026-04-20: Galaxy Clusters Underestimated Baryonic Matter Challenges Dark Matter · ▶ source