 Luminosity function (astronomy)

An astronomical luminosity function gives the number density of objects per luminosity interval, often also per comoving volume. Integrating luminosity times the function gives their luminosity density.

In astronomy, the luminosity function is a statistical distribution that describes the number of stars (or other celestial objects) per unit volume as a function of their luminosity. It provides an important tool for understanding the population of stars in a given region of space and how these stars are distributed in terms of their brightness and energy output. The luminosity function is often expressed as \( \phi(L) \), which represents the density of stars with a given luminosity \( L \).