Astrophysics & Particle Physics-APPC 2026

Quasars (quasi-stellar objects) are among the universe's brightest and most energetic objects, fueled by supermassive black holes in the centers of galaxies with accretion of matter. They are a form of active galactic nucleus (AGN) and radiate huge amounts of energy in all wavelengths of the electromagnetic spectrum, from radio waves to X-rays and gamma rays.The central accretion disk surrounding the supermassive black hole is able to transform gravitational energy into radiation, creating the high luminosity that is observed from quasars. Quasars often also show relativistic jets, beams of charged particles expelled at close to the speed of light, that extend over thousands of light-years and radiate intensely in radio frequencies.Quasars appear at high redshifts and so are valuable probes of the early universe. Quasar spectroscopy unveils the chemical makeup, velocity, and distribution of interstellar and intergalactic matter, making statements about galaxy formation, evolution, and structure of the cosmos.Quasars show variability over timescales ranging from days to years, echoing transient processes in the accretion disk, jet, and black hole surroundings.

Multi-wavelength observations, such as optical, radio, X-ray, and infrared astronomy, are vital to understand their physical processes and energy production.High-energy quasars impact their host galaxies by regulating the formation of stars and galactic evolution through feedback processes.Radiation and jets are responsible for this regulation. They play an essential role in comprehending supermassive black hole growth and the interaction between black holes and the surrounding matter.Quasars provide astronomers with the opportunity to learn about extreme gravitational, relativistic, and high-energy processes. Quasars are cosmic lighthouses that shed light on the makeup and development of the early universe and offer a special window into supermassive black hole and active galactic nucleus physics.