An Etymological Dictionary of Astronomy and Astrophysics

The integrated intensity of all of the light emitted throughout the history of the Universe across the whole of the → electromagnetic spectrum,
including those which are not individually detected. The EBL spectrum includes cosmological backgrounds associated with either primordial phenomena, such as the → cosmic microwave background radiation (CMBR),
or photons emitted by stars, galaxies and → active galactic nuclei (AGN) due to → nucleosynthesis or other → radiative processes, including → dust scattering, → absorption and reradiation. The EBL may also contain signals that are diffuse and extended, including high-energy photons associated with dark matter particle decays or annihilation.

See also: → extragalactic; → background; → light.