What is the source of the power of an Active galactic nucleus or Quasar? We look at the Supermassive black holes that create these amazing objects. • Central Engine of Active Galaxies: Extraordinarily luminous objects emitting huge amounts of non-stellar energy, exhibiting variability and signs of explosive activity. • Characteristics of Active Galactic Nuclei (AGN): Luminosities billions to trillions of times that of the Sun, emitting across a wide range of wavelengths, and exhibiting rapid variability in brightness. • Black Hole Paradigm for AGN: The energy source is explained by the accretion of matter onto a supermassive black hole, with masses ranging from millions to billions of times that of the Sun. • Supermassive Black Hole Size: They are extraordinarily huge, with a diameter larger than Saturn’s orbit, despite the black hole itself being small compared to the accretion disk and jets. • Accretion Disk and X-ray Emission: Material falling into the black hole forms a hot accretion disk, emitting light, particularly X-rays, as it heats up due to friction. • Jet Formation: The accretion disk’s magnetic fields, twisted into a toroidal shape, can contain and propel material outwards in a jet. • Black Hole Energy Source: Black holes are extremely efficient at transforming matter into energy, with up to 20% of the rest mass of infalling material being converted into light. • Quasars: Quasars are the most powerful type of AGN, representing extremely luminous active galactic nuclei. • M87 Black Hole Observation: Observations of M87, a supermassive elliptical galaxy, reveal a large amount of gas orbiting its central black hole at high speeds, exhibiting both red and blue shifts in their spectra. • Jet Formation and Properties: The jet originates from a region about seven parsecs away from the black hole, with its base having a diameter five times the Schwarzschild radius of the black hole. • Active Galactic Nuclei Appearance: Explained by the orientation of radio lobes and jets, with different appearances depending on whether the jet is viewed directly or from the side. • Model of Active Galactic Nuclei: An accretion disk around a supermassive black hole, which is relatively small compared to the size of the galaxy. • X-ray Emission Source: X-ray emission originates from the central region of an active galactic nucleus, potentially within a few astronomical units. • Supermassive Black Hole in Centaurus A: Centaurus A has a supermassive black hole at its center with a mass of 55 million solar masses, which is responsible for the jets. • Synchrotron Radiation: Electrons spiraling around magnetic fields emit synchrotron radiation, contributing to radio and x-ray emissions in active galactic nuclei. • Active Galactic Nucleus Signature: Active galactic nuclei are characterized by strong radio and x-ray emissions, with a relatively flat spectrum, indicating non-thermal radiation processes. Overall, the segment emphasizes clear definitions, underlying geometry, and practical observing guidance so viewers can connect the concept to the real sky.