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 modeling and increasingly deep astronomical observations.
Early Universe Observations
The James Webb Space Telescope (JWST) has provided evidence for unexpectedly early galaxy formation and massive galaxies in the first billion years of cosmic history. Observations of the galaxy GN-z11, among others, suggest the presence of Population III stars—the earliest generation of stars composed primarily of hydrogen and helium—in the early universe. These observations constrain models of how the first galaxies acquired their mass and enriched the intergalactic medium with heavier elements.
Formation Mechanisms
Galaxies are thought to form through the gravitational collapse of dark matter and gas in the early universe, with small structures merging over time to build larger systems. The exact mechanisms driving rapid early galaxy assembly, including star formation rates and the role of supermassive black holes, remain active areas of investigation. Modern cosmological simulations attempt to reproduce observed galaxy populations, though discrepancies between theory and observation persist, particularly regarding the properties of galaxies in the universe’s first few hundred million years.
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