Final answer:
Peculiar velocities, detected by observing the rotation speeds of galaxies and stars, suggest the presence of dark matter, which impacts the gravitational dynamics of large-scale structures in the universe.
Step-by-step explanation:
The correct option : b
These observations indicate that a significant amount of mass, which does not emit or absorb electromagnetic radiation detectable to us—known as dark matter—influences the gravitational dynamics of galaxies and clusters.The work of Fritz Zwicky and Vera Rubin was instrumental in uncovering this phenomenon. They observed that stars farther from the galactic center were moving at unexpected velocities, suggesting the presence of more mass than could be accounted for by visible matter.
The consistent, high velocities of stars and gas at the outer edges of galaxies indicate that a halo of dark matter extends well beyond the visible components of galaxies.Furthermore, the observation of hot, ionized gas emitting X-rays from regions between galaxies supports the existence of dark matter in large-scale structures. These and other observations have led astronomers to conclude that dark matter has a significant effect on the formation and evolution of galaxies, playing a dominant role in the universe's large-scale structure.