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Astronomy

The Luminosity Function of Galaxies and Its Evolution

Quick fact

The luminosity function of galaxies in the local universe is well described by the Schechter function, which shows that faint galaxies outnumber bright ones by a large margin. Yet, in the early universe, the bright end of the luminosity function was relatively more populated, indicating that the brightest galaxies were more common then.

Why this is interesting

The night sky is packed with galaxies, but they are not all equally bright. Why do astronomers think the distribution of galaxy brightness has changed dramatically over cosmic time?