Astrophysics & Particle Physics-APPC 2026

Active Galactic Nuclei (AGN) are the very luminous nuclei of some galaxies, fueled by accretion onto supermassive black holes. As matter accretes into the black hole's accretion disk, gravitational potential energy is dissipated as radiation throughout the electromagnetic spectrum, making AGN among the brightest and most luminous objects in the universe.The unified scheme of AGN postulates that these types are various angles and orientations of a single underlying process: a supermassive black hole, an accretion disk, broad and narrow line emission regions, and relativistic jets.AGN are important for galaxy evolution via feedback mechanisms, in which energy and radiation from the nucleus control star formation and shape the intergalactic medium. AGN jets stretch over millions of light-years, fueling nearby gas and regulating the large-scale galaxy and cluster environment.Wildly variable AGN require observations across multiple wavelengths, from radio and infrared, to optical, ultraviolet, X-ray, and gamma-ray observations. AGN brightness variability gives us a window into accretion, jet, and black hole growth over cosmic history.

Digging into AGN informs astronomers about the co-evolution of galaxies and their central black holes, the physics of high-energy astrophysical phenomena, and how AGN shape cosmic structure formation.Active Galactic Nuclei continue to be a hot topic in astrophysics, providing access to the most extreme environments in the universe and the underlying processes that link black hole activity with the evolution of galaxies.