In the Hubble Word Bank, AGNs and quasars are explained thoroughly. Essentially, an AGN is a compact area at the core of specific galaxies (known as active galaxies) that emits far more brightness than the galaxy's stars alone. This increased luminosity results from the presence of a supermassive black hole at the galaxy's center. Rather than directly falling into the black hole, matter is drawn into a swirling disc before being inexorably pulled towards it. This matter-packed disc becomes extremely hot, emitting a vast amount of energy across the electromagnetic spectrum and causing AGNs to shine brightly.
Quasars are a specialized type of AGN, displaying extreme brightness and lying at vast distances from Earth, with several hundred million light-years still considered close. Z 229-15, being relatively nearby, is an example of this. In some cases, an AGN's luminosity is so intense that the rest of the galaxy is obscured. However, Seyfert galaxies are active galaxies that host remarkably bright AGNs (quasars) while remaining observable. Thus, Z 229-15 is a Seyfert galaxy containing a quasar, which, by definition, also hosts an AGN. Astronomical classification can indeed be challenging!
Image Description: A spiral galaxy featuring two nearly straight arms extending from the left and right of the core, converging at a star-filled, bluish ring around the galaxy's edge. The core glows a golden hue, surrounded by a faint halo of light. A single bright star with multiple diffraction spikes and several smaller stars are scattered against the black background.
Credit: European Space Agency (ESA)/Hubble & NASA, A. Barth, R. Mushotzky
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