Which two primary models are studied to understand the process of mass buildup in the most massive galaxies across cosmic time?
Major Mergers and Steady Accretion
When astronomers study the epoch around 10 billion years ago (redshifts z ≈ 1 to 3), which is considered the peak of star formation, they analyze how massive galaxies achieved their size. Two competing or complementary pathways for mass buildup are investigated. The first is Major Mergers, which suggests rapid growth fueled by the violent collision and fusion of two similarly sized smaller systems. The alternative is Steady Accretion, which posits a slower, more continuous accumulation of mass through the gradual drawing in of gas and smaller satellite galaxies onto a central host. Observing the morphology of galaxies during this peak epoch helps determine the relative prevalence of these two fundamental growth mechanisms.
