Extragalactic cosmic ray Extragalactic cosmic ray Extragalactic cosmic rays are very-high-energy particles that flow into the Solar System from beyond the Milky Way galaxy. The energies these particles possess are in excess of 10 eV. Unlike solar or galactic cosmic rays, little is known about the origins of extragalactic cosmic rays. This is largely due to a lack of statistics: only about 1 extragalactic cosmic ray particle per square meter per year reaches the Earth's surface (see figure). There are many ideas about which processes may be responsible for cosmic rays with such high energies. In the 'bottom-up' approach, cosmic rays gain more
Diffuse extragalactic background radiation Diffuse extragalactic background radiation The diffuse extragalactic background radiation (DEBRA) refers to the diffuse photon field from extragalactic origin that fills our Universe. It contains photons over ∼ 20 decades of energy from ~10 eV to ~100 GeV. The origin and the physical processes involved are different within every wavelength range. There are plenty of observational evidences that support the existence of the DEBRA. The figure shows a schematic picture, based on many different data sets, of the spectral intensity (also called spectral radiance) multiplied by wavelength of the DEBRA over all the electromagnetic spectrum. This representation is convenient because