Active galactic nucleus
Active galactic nucleus is a compact region at the center of a galaxy that emits large amounts of energy across the electromagnetic spectrum. It is associated with accretion onto a supermassive black hole.
Active galactic nuclei are discussed in astrophysics, extragalactic astronomy, and high-energy astronomy.
Status
Active galactic nuclei are identified through their spectral properties, variability, and energetic emissions. Models describe their structure, energy output, and interaction with host galaxies, and continue to be refined.