A quasar is an extremely luminous active galactic nucleus (AGN) powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses. Quasars are sometimes known as quasi-stellar objects (QSOs) because they appear star-like when viewed from Earth. They are the most luminous objects in the known universe and are visible from extreme distances.
Key features of quasars include:
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Enormous Luminosity: Quasars emit energies of millions, billions, or even trillions of electron volts, exceeding the total light output of all the stars within a galaxy. They shine anywhere from 10 to 100,000 times brighter than the Milky Way.
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Supermassive Black Hole: Quasars are believed to produce their energy from massive black holes in the center of the galaxies in which they are located. These black holes contain billions of times the mass of the sun and are fed by gas supplies, perhaps supplied by a recent galaxy-galaxy collision.
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Distance: Quasars are observed from Earth as they were when the light we see left them, meaning that the nearest quasars to Earth are still several hundred million light-years away. The oldest quasar currently known is J0313-1806, which is approximately 13.03 billion light-years away.
Despite their brightness, quasars are so small and distant that even the most powerful telescope cannot resolve all the structures. Quasars emit radiation across the electromagnetic spectrum, including visible and ultraviolet light, X-rays, and gamma-rays.
In summary, a quasar is an extremely luminous active galactic nucleus powered by a supermassive black hole. They are the most luminous objects in the known universe and are visible from extreme distances. Quasars emit radiation across the electromagnetic spectrum and are believed to produce their energy from massive black holes in the center of galaxies.
